Well, Quicksilver was a way of life for me until this summer. When I upgraded from Panther to Tiger, I decided to force myself to give Spotlight a try. I'm done with it, and now back into using the superb launcher and do it all Quicksilver. If you've never heard of the utility... you owe it to yourself to give it a try. QS allows you to have access to anything quickly (like you do with Spotlight), but then allows you to do an incredible array of actions with that item. You can launch apps, but you can email documents, append to them, run scripts and actions on them, all from a quick keyboard interface. QS allows you to create system-wide key combinations to actions (like Quickkeys), and it's much faster at finding items than Spotlight, since Spotlight is searching for metadata, not simpy file names.
Give it a download and peruse these tutorials to get you started.
There are other options in the "launcher" arena, mostly Butler and Launchbar. If you're a fan of either of these, it's probably worth you just sticking it out with what you're used to... but if you're new to the genre, Quicksilver is definitely the way to go.