The big one that I went through recently was killing startup items. You tend to hoard them over time, especially with a dev machine.
Look in, and clear out in /Library/StartupItems and /System/Library/StartupItems
Like any good UNIX, there are a dozen other ways that applications can launch themselves in OS X, so run a ps and find processes that you don't need and figure out where they are being started.
I alias everything in bash to run the scripts manually when I need them (eg. 'apu' starts apache, 'ngu' starts nginx, 'vbx' sets up virtualbox). Saves a ton of memory and gets boot time down to seconds rather than minutes.
Look in, and clear out in /Library/StartupItems and /System/Library/StartupItems
Like any good UNIX, there are a dozen other ways that applications can launch themselves in OS X, so run a ps and find processes that you don't need and figure out where they are being started.
I alias everything in bash to run the scripts manually when I need them (eg. 'apu' starts apache, 'ngu' starts nginx, 'vbx' sets up virtualbox). Saves a ton of memory and gets boot time down to seconds rather than minutes.