It's funny. I used to use Psi, but then I switched to iChat. I used to use Quicksilver, then I switched to Launchbar, and now I just use Spotlight. I have Homebrew, because MacPorts can't install 3.2 of GNU Smalltalk and for no other reason. I haven't installed Dropbox ever, or Skitch (never heard of it, will check it out) or Divvy (I think I downloaded a demo of it once, thought it would be cool, and never went back to buy it).
I don't know what my problem is, but I guess my need for new features keeps diminishing. Maybe in forty years I'll finally be able to use Plan 9.
I went from LaunchBar to Quicksilver to Spotlight to LaunchBar. Can't live without that clipboard history! I don't use many of its other features anymore though.
Preview annotates things well enough that I never use Skitch, although Skitch is cool if you want to use the sharing features.
You might be missing out on Dropbox. I wouldn't want to go without it these days as I use more than one computer regularly and don't have to remember to commit 'WIP' on a branch before I head home, I just drop the mic and get the fuck out. YMMV.
Divvy is great. I use it w/ SizeUp every day and wouldn't want to go without them. I don't miss xmonad at all anymore.
Other than that I install 1Password, The Unarchiver, Growl, CrashPlan, Flux, TextMate, iTerm, and GitX and I am good to go.
I seem to shed tools as OS X improves as well, but I hope that nobody is using plan9 in 40 years! ;-)
Agree on TextMate. Haven't heard of most of the other stuff. I used Xmonad for about six months, then I basically copied the keybindings into an fvwm config, then I switched to KDE, brought over a handful of the keybindings and I seem to be alright.
I would probably use Dropbox if I didn't have a VM. A friend has been trying to get me to use one of their competitors for a while.
Plan 9 is great, just a bit too much ideology to actually get anything done. I hope it's still maintained in 40 years in case I do go that way. :)
I don't know what my problem is, but I guess my need for new features keeps diminishing. Maybe in forty years I'll finally be able to use Plan 9.