If you haven’t tried out TextMate I command you to download it right now. Its the most powerful and flexible editor I have ever used, I’m having trouble understanding how everything works its complicated. The syntax coloring is amazing, its so incredibly customizable. This is the only Cocoa text-editor I’m aware of that has code-folding, which is a very cool feature. The documentation is awesome and the wiki and mailing list are awesome resources too. It has amazing integration with the command line, allowing almost endless customization!