TranscendLinux.com

Here are some great resources on mod_rewrite from apache.org:
http://httpd.apache.org/docs/1.3/misc/rewriteguide.html: This guide provides some great examples for common uses of mod_rewrite, including things like using rewrite to rewrite urls from a moved document root, rewriting all subdomains to a primary subdomain (e.g. have *.test.com all be rewritten to test.com), etc.
http://httpd.apache.org/docs/2.0/mod/mod_rewrite.html: Full documentation on mod_rewrite.
http://www.ilovejackdaniels.com/mod_rewrite_cheat_sheet.png: Spiffy Cheatsheet