The YUI Gallery is a collection of community-contributed YUI modules. Many of these modules are released under the BSD license and are available via Yahoo!'s CDN, making them as easy to use() as core YUI components.
Keep an eye on the YUI Blog for announcements about releases and community events, as well as in-depth technical posts from members of the YUI team and the community.
Have a question about YUI? Want to show off something cool you've built? Head to the forums! Community experts and YUI team members are always on hand to answer your questions and offer guidance.
YUI Theater is a large and ever-growing collection of videos about all things web-related (not just YUI!).
Whether you're new to web development or just eager to learn from respected experts like Douglas Crockford, John Resig, Nicholas Zakas, and others, YUI Theater contains a wealth of valuable knowledge.