Quicksilver

I find that Quicksilver is becoming more and more of an indespensible part of my Mac OS X installation. The more you use it, the more useful it becomes, so the trick is to make yourself use it in the first place. It seems that everyone has a different aspect of Quicksilver that addicts them to it. For me, it's the ability to quickly find a track in iTunes and make it the next item in Party Shuffle. No switching away from the app I'm in, just a few key strokes. And as this became more and more of a habit, I found that I was using the Finder less, since it was so easy to launch apps and documents from Quicksilver too. Gotta love it.