A quick reference guide for regular expressions (regex), including symbols, ranges, grouping, assertions and some sample patterns to get you started.
A quick reference guide for PHP, with functions references, a regular expression syntax guide and a reference for PHP's date formating functions.
A mod_rewrite Cheat Sheet - a quick reference guide for mod_rewrite, with rewrite flags, regular expression syntax and sample rules.
A quick reference for HAML. See more information about HAML here: http://haml-lang.com/docs/yardoc/file.HAML_REFERENCE.html
Python cheat sheet
A cheat sheet for the MySQL database.
List of common jQuery selectors. I had compiled this list a while ago into a word document but do not remember the source now.
CoffeeScript cheat sheet compiled after following "CoffeeScript Koans" from sleepyfox
Subversion cheat sheet
The advanced methods available with the Vimeo API.
Cheat Sheets by Tag