A PHP script and style file for generating rendered HTML from Markdown for pasting into mail messages. I use it instead of WYSIWYG editing in Rich Text mode because I'm so used to working in Markdown.

I run this from TextMate using the Mail Preview command:

the text of the command is

php ~/mail-preview/mail-preview.php > ~/mail-preview/mail-preview.html
open ~/mail-preview/mail-preview.html

When invoked, this command passes the Markdown in the current document to the mail-preview.php script and generates a new mail-preview.html file, which is then opened in the default browser.

I then copy the text from the browser and paste it into either Mail.app or GMail's Compose field.

Note:
The script relies on some form of PHP Markdown (I use my own PHP Markdown Extra Math) and PHP SmartyPants to be on the local computer. The paths to these libraries are specified in Lines 3 and 4 of mail-preview.php.