A Great Start for your next Magento Theme's local.xml file -
<?xml version="1.0"?>
<layout>
<!--
Add/Remove Items From Head
-->
<default translate="label" module="page">
<reference name="head">
<!-- Add Javascript File -->
<action method="addItem"><type>skin_js</type><name>js/jquery.js</name><params/></action>
<!-- Add CSS File -->
<action method="addCss"><stylesheet>css/local.css</stylesheet></action>
</reference>
</default>
<!--
Default layout, loads most of the pages
-->
<default>
<!-- Add Custom Block
<reference name="root">
<block type="core/template" before="-" name="my_block" as="my_block" template="path/to/file.phtml"/>
</reference>
-->
<!-- Header -->
<reference name="header">
<!-- Insert Code Here -->
</reference>
<!-- Left Sidebar -->
<reference name="left">
<!-- Insert Code Here -->
</reference>
<!-- Right Sidebar -->
<reference name="right">
<remove name="right.poll" />
</reference>
<!-- Content -->
<reference name="content">
<!-- Insert Code Here -->
</reference>
<!-- Top Nav -->
<reference name="top.nav">
<!-- Insert Code Here -->
</reference>
</default>
<!--
CMS Layout
-->
<cms_page>
<!-- Header -->
<reference name="header">
<!-- Insert Code Here -->
</reference>
<!-- Left Sidebar -->
<reference name="left">
<!-- Insert Code Here -->
</reference>
<!-- Right Sidebar -->
<reference name="right">
<!-- Insert Code Here -->
</reference>
<!-- Content -->
<reference name="content">
<!-- Insert Code Here -->
</reference>
</cms_page>
<!--
CMS Homepage
-->
<cms_index_index>
<!-- Header -->
<reference name="header">
<!-- Insert Code Here -->
</reference>
<!-- Left Sidebar -->
<reference name="left">
<!-- Insert Code Here -->
</reference>
<!-- Right Sidebar -->
<reference name="right">
<!-- Insert Code Here -->
</reference>
<!-- Content -->
<reference name="content">
<!-- Insert Code Here -->
</reference>
</cms_index_index>
<!--
Catalog Category Layout
-->
<catalog_category_default translate="label">
<!-- Insert Code Here -->
</catalog_category_default>
<!--
Catalog Product View Layout
-->
<catalog_product_view translate="label">
<!-- Insert Code Here -->
</catalog_product_view>
<!--
Catalog Layered Layout
-->
<catalog_category_layered translate="label">
<!-- Insert Code Here -->
</catalog_category_layered>
<!--
Catalog Search Results Layout
-->
<catalogsearch_result_index translate="label">
<!-- Insert Code Here -->
</catalogsearch_result_index>
<!--
Catalog Advanced Search Layout
-->
<catalogsearch_advanced_index translate="label">
<!-- Insert Code Here -->
</catalogsearch_advanced_index>
<!--
Catalog Advanced Search Results Layout
-->
<catalogsearch_advanced_result translate="label">
<!-- Insert Code Here -->
</catalogsearch_advanced_result>
<!--
Cart Template
-->
<checkout_cart_index translate="label">
<!-- Insert Code Here -->
</checkout_cart_index>
<!--
OnePage Layout
-->
<checkout_onepage_index>
<!-- Insert Code Here -->
</checkout_onepage_index>
<!--
OnePage Success Layout
-->
<checkout_onepage_success>
<!-- Insert Code Here -->
</checkout_onepage_success>
<!--
Contact Page Template
-->
<contacts_index_index translate="label">
<!-- Insert Code Here -->
</contacts_index_index>
<!--
Customer Account Layout
-->
<customer_account>
<!-- Insert Code Here -->
</customer_account>
<!--
Customer Account
-->
<customer_account>
<!-- Insert Code Here -->
</customer_account>
<!--
Customer Login Page
-->
<customer_account_login>
<!-- Insert Code Here -->
</customer_account_login>
<!--
Customer Forgot Password
-->
<customer_account_forgotpassword>
<!-- Insert Code Here -->
</customer_account_forgotpassword>
<!--
Customer Logged In
-->
<customer_logged_in>
<!-- Insert Code Here -->
</customer_logged_in>
<!--
Customer Logged Out
-->
<customer_logged_out>
<!-- Insert Code Here -->
</customer_logged_out>
</layout>
<!-- List of Usefull Removals
<remove name="catalog.compare.sidebar" />
<remove name="right.permanent.callout" />
<remove name="left.permanent.callout" />
<remove name="left.newsletter" />
<remove name="right.reports.product.viewed" />
<remove name="paypal.partner.right.logo" />
<remove name="right.poll" />
<remove name="cart_sidebar" />
<remove name="checkout_cart_link" />
<remove name="catalog.compare.list" /> -->
default
catalog_category_default (* also used in directory.xml)
catalog_category_layered (* also used in directory.xml)
catalog_product_compare_index
catalog_product_gallery
catalog_product_send
catalog_product_view (* also used in customeralert.xml, tag.xml)
catalog_seo_searchterm_popular
catalog_seo_sitemap_category
catalog_seo_sitemap_product
catalogsearch_advanced_form
catalogsearch_advanced_result
catalogsearch_result_index
catalogsearch_term_popular
checkout_cart_index (* also used in googlecheckout.xml, paypal.xml)
checkout_multishipping
checkout_multishipping_address_editaddress
checkout_multishipping_address_editbilling
checkout_multishipping_address_editshipping
checkout_multishipping_address_newbilling
checkout_multishipping_address_newshipping
checkout_multishipping_address_select
checkout_multishipping_address_selectbilling
checkout_multishipping_addresses
checkout_multishipping_billing
checkout_multishipping_customer_address
checkout_multishipping_login
checkout_multishipping_overview
checkout_multishipping_register
checkout_multishipping_shipping
checkout_multishipping_success
checkout_onepage_additional
checkout_onepage_index
checkout_onepage_progress
checkout_onepage_review
checkout_onepage_shippingmethod
checkout_onepage_success
cms_index_defaultindex
cms_index_defaultnoroute
customer_account (* also used in newsletter.xml, review.xml, sales.xml, wishlist.xml)
customer_account_create
customer_account_edit
customer_account_forgotpassword
customer_account_index (* also used in catalog.xml, newsletter.xml, poll.xml, review.xml, sales.xml, tag.xml, wishlist.xml)
customer_account_login
customer_address_form
customer_address_index
customer_logged_in
customer_logged_out
customer_account_logoutsuccess
giftmessage_index_edit
giftmessage_index_save
giftmessage_index_remove
newsletter_manage_index
paypal_express_review
paypal_express_review_details
print
review_customer_index
review_customer_view
review_product_list
review_product_view
reviews
sales_order_details
sales_order_history
sales_order_print
sales_order_view
shipping_tracking_ajax
tag_customer_index
tag_customer_edit
tag_customer_view
tag_list_index
wishlist_index_indexaddPriceBlockType: <action method="addPriceBlockType"><type>bundle</type><block>bundle/catalog_product_price</block><template>bundle/catalog/product/price.phtml</template></action>
addItemRender: <action method="addItemRender"><type>bundle</type><block>
bundle/checkout_cart_item_renderer</block><template>checkout/cart/sidebar/default.phtml</template></action>
addItem: <action method="addItem"><type>skin_js</type><name>js/bundle.js</name></action>
insert: <action method="insert"><block>product.info.bundle.options</block></action>
setItemLimit: <action method="setItemLimit"><type>bundle</type><limit>4</limit></action>
setImgSrc: <action method="setImgSrc"><src>images/media/col_left_callout.jpg</src></action>
setImgAlt: <action method="setImgAlt" translate="alt" module="catalog"><alt>Our customer service is available 24/7. Call us at (800) DEMO-NUMBER.</alt></action>
setLinkUrl: <action method="setLinkUrl"><url>checkout/cart</url></action>
addLink: <action method="addLink" translate="label title" module="catalog" ifconfig="catalog/seo/site_map"><label>Site Map</label><url helper="catalog/map/getCategoryUrl" /><title>Site Map</title></action>
setDefaultListPerPage: <action method="setDefaultListPerPage"><limit>4</limit></action>
setDefaultGridPerPage: <action method="setDefaultGridPerPage"><limit>9</limit></action>
addPagerLimit: <action method="addPagerLimit"><mode>list</mode><limit>6</limit></action>
setToolbarBlockName: <action method="setToolbarBlockName"><name>product_list_toolbar</name></action>
addReviewSummaryTemplate: <action method="addReviewSummaryTemplate"><type>default</type><template>review/helper/su.phtml</template></action>
setTemplate: <action method="setTemplate"><template>page/one-column.phtml</template></action>
addJs: <action method="addJs"><script>scriptaculous/scriptaculous.js</script></action>
unsetChild: <action method="unsetChild"><name>catalog_compare_sidebar</name></action>
setTierPriceTemplate: <action method="setTierPriceTemplate"><template>catalog/product/view/tierprices.phtml</template></action>
setColumnCount: <action method="setColumnCount"><columns>4</columns></action>
setItemLimit: <action method="setItemLimit"><type>upsell</type><limit>4</limit></action>
addOptionRenderer: <action method="addOptionRenderer"><type>text</type><block>catalog/product_view_options_type_text</block><template>catalog/product/view/options/type/text.phtml</template></action>
insert: <action method="insert"><block>product.tierprices</block></action>
append: <action method="append"><block>product.info.addtocart</block></action>
setDataByKey: <action method="setDataByKey"><key>alias_in_layout</key><value>container2</value></action>
setDataByKeyFromRegistry: <action method="setDataByKeyFromRegistry"><key>options_container</key><key_in_registry>product</key_in_registry></action>
unsetCallChild: <action method="unsetCallChild"><child>container1</child><call>ifEquals</call><if>0</if><key>alias_in_layout</key><key>options_container</key></action>
setTitle: <action method="setTitle" translate="title" module="catalog"><title>Categories</title></action>
bindPager: <action method="bindPager"><pager>seo.sitemap.pager.top</pager></action>
setItemsTitle: <action method="setItemsTitle" translate="title" module="catalog"><title>categories</title></action>
setListOrders: <action method="setListOrders"/>
setListModes: <action method="setListModes"/>
setListCollection: <action method="setListCollection"/>
addCartLink: <action method="addCartLink"></action>
addCheckoutLink: <action method="addCheckoutLink"></action>
setCartTemplate: <action method="setCartTemplate"><value>checkout/cart.phtml</value></action>
setEmptyTemplate: <action method="setEmptyTemplate"><value>checkout/cart/noItems.phtml</value></action>
chooseTemplate: <action method="chooseTemplate"/>
setMethodFormTemplate: <action method="setMethodFormTemplate"><method>purchaseorder</method><template>payment/form/purchaseorder.phtml</template></action>
setInfoTemplate: <action method="setInfoTemplate"><method></method><template></template></action>
setDontDisplayContainer: <action method="setDontDisplayContainer"><param>1</param></action>
setBlockId: <action method="setBlockId"><block_id>footer_links</block_id></action>
setHeaderTitle: <action method="setHeaderTitle" translate="title" module="contacts"><title>Contact Us</title></action>
setSaveMode: <action method="setSaveMode"><mode>save</mode></action>
setGoogleCheckout: <action method="setGoogleCheckout"><flag>true</flag></action>
setScriptType: <action method="setScriptType"><scriptType>control_script</scriptType></action>
addCss: <action method="addCss"><stylesheet>css/reset.css</stylesheet></action>
setPollTemplate: <action method="setPollTemplate"><template>poll/active.phtml</template><type>poll</type></action>
addWishlistLink: <action method="addWishlistLink"></action>
addBodyClass: <action method="addBodyClass"><className>account</className></action>core/template: This block renders a template defined by its template attribute. The majority of blocks defined in the layout are of type or subtype of core/template.
page/html: This is a subtype of core/template and defines the root block. All other blocks are child blocks of this block.
page/html_head: Defines the HTML head section of the page which contains elements for including JavaScript, CSS etc.
page/html_header: Defines the header part of the page which contains the site logo, top links, etc.
page/template_links: This block is used to create a list of links. Links visible in the footer and header area use this block type.
core/text_list: Some blocks like content, left, right etc. are of type core/text_list. When these blocks are rendered, all their child blocks are rendered automatically without the need to call thegetChildHtml() method.
page/html_wrapper: This block is used to create a wrapper block which renders its child blocks inside an HTML tag set by the action setHtmlTagName. The default tag is <div> if no element is set.
page/html_breadcrumbs: This block defines breadcrumbs on the page.
page/html_footer: Defines footer area of page which contains footer links, copyright message etc.
core/messages: This block renders error/success/notice messages.
page/switch: This block can be used for the language or store switcher.