After using Quicksilver for some time, I've actually switched to Butler
. It does just about all the same things as Quicksilver, but it seems much faster.
Another nifty trick I do with QS/Butler is assign a hotkey to an app. When activated, it will either launch the app or simply bring it to the fore if it's already running. I use all three lower meta keys (control+option+cmd -- to avoid app collisions) plus a letter.
By using an app like this to launch your apps, your dock basically only has running apps. No longer do you need 50 icons so you can launch things. They only appear on the dock (running) when you launch them via QS/Butler.
Also, I liked Menumeters, but I find I like iStat Menus
One more: RCDefaultApp
lets you set your default app for different file types easily and all in one place. This should have been bundled with OSX!