I've been lucky to run xmonad on OSX from Snow Leopard to Mountain Lion. Here's my OSX stack (to be automated with chef).
with xmonad, git, vim, tmux, iTerm2. Ports are installed from binary packages instead of compiled. I have multiple MacPorts distributions that vendor ports to support specific applications.
with ree, 1.9.3, jruby. I also use rbenv on top of rvm when the rbenv interface is better suited for my scripts.
with Pentadactyl, Adblock Plus, Greasemonkey, Secure Login, TACO, Duck Duck Go SSL search, HTTPS Everywhere. Window decorations turned off so it's all content space.
I use proprietary software and even pay for some!
When I must go into OSX, SizeUp provides basic tiling window management.
Gives me CMD-TAB (xmonad) and CAPSLOCK as CTRL-B (tmux). Combine this with a Kinesis keyboard with hardware key mapping and macros.
I love this kind of bling.
Mainly to add Quit to the Finder. Lots of other good tweaks.
Stores my OSX stack after I've brought up Dropbox.
Stores my passwords, keys. Synced to Dropbox. I use randomly generated login/email addresses with strong passwords.
When I need to access my S3 buckets.
Making bootable copies on a USB disk, second disk on the computer, and bootable recovery USB thumb drives.
with vagrant to run Ubuntu, where I do my real work.
Staying up to date with my stack.