BBEdit
There are many text editors out there. Sadly, most of them suck. BBEdit’s motto is “BBEdit sucks less”, and they’re right. Bare Bones, the creators of BBEdit have created a plain text editor that works the way I work. Because I am a geek, I tend to create or find scripts that help me get things done faster. BBEdit integrates with the various script interpreters (Perl, Shell, AppleScript, etc.) on your Mac to allow for an ever expanding array of features. Highlight a bit of text, and you can select any script to run via a menu item, using the text as input. There are a few features that would make BBEdit suck even less, such as collapsible code blocks, but I am sure they’ll appear in a near-future version.
I code everything by hand. I’ve found that WYSIWYG editors don’t create solid, semantic code. This makes them useless to me, even for rapid prototyping. With BBEdit, I have the ability to write code, validate, debug, and view results directly within the application. This allows me to build prototypes faster, making my clients happy. We like happy clients, and that’s why BBEdit is in my toolbox.