TextWrangler is my text editor of choice. It's a free download from Bare Bones Software, and is the younger brother of BBEdit. Most of the functionality of BBEdit is present in TextWrangler, which is why I love it so much. Syntax highlighting, "edit" command from Terminal, a very comprehensive find/replace... there's no shortage of tools. Text files exist under a lot of different names, so it's nice to have one familiar environment to edit them. It's also pretty lightweight, so I've always got it running, ready to handle my text.

I use TextWrangler to edit php, shell scripts, XML, flash LoadVars files, simple text documents containing content, and (occasionally) .as files. I've tried several other editors, but they were either not free or not as fast and capable as this one. It's nice when working with many, many different computers to be able to go online, grab an application, install it, and have a familiar editing environment; TextWrangler gives me this option.

The download page for TextWrangler can be found on the Bare Bones Software website. It's an OS X application.