!TextMate is a popular programmers-editor for OS X.
Homepage: http://macromates.com/

One of the most interesting feature is the ability to define "Snippets", abbreviations which can be expanded into larger blocks of text.

This advert was brought to you by Wiki-Spam: using other people's trusting nature for their own ends.

Remember: winners use Vim.

ubernostrum sez: I can attest that in the office where Django is developed, TextMate users are in abundance. Gosh, aren't wikis fun?