TextMate and RubyMine (Ruby and Rails), Eclipse (AppEngine, Wave robot dev), IntelliJ (Java), AquaEmacs and SBCL/Franz/Gambit-C (Common Lisp and Scheme).<p>For documentation/writing: OmniGraffle and Latex (and sometimes Page or OpenOffice.org)
I do a lot of django and drupal development so I use screen, vim, terminal, hg/git/svn, virtualenv and MAMP. I also use firefox with firebug, and the Live HTTP headers plugin, and virtualbox for virtual windows and linux environments.
I use xcode, textmate, cyberduck for sftp, gitx for basic git usage, terminal for most of the heavy lifting, vim on servers. Photoshop when needed to tweak something minor but mostly I am a programmer.
I tried using Aquamacs for a long time, but it didn't work out, and I just switched back to 'plain emacs' now that the mac version builds out of cvs.
I also use iTerm, Fabric, django, mysql and svn.
I use SubEthaEdit or TextWrangler depending on what I'm writing. SubEthaEdit has better syntax highlighting for some things, including Go, but TextWrangler acts more like I want it to.
My most common applications in my workflow are Coda, Terminal, and Fireworks for the occasional graphics editing. Also, XCode is a big player when I'm doing my iPhone development.
TextMate for code and SequelPro for MySQL. The rest is built in: Terminal, Apache + PHP. Also, I off-and-on use Things for task lists (now I'm back on using TODOs in Textmate).