Quicksilver for Windows - Eh...soon...Colibri is close
I am so very much all about SlickRun, but lately I've been branching out.
I've been using the "Ctrl-Ctrl" hotkey on Google Desktop more and more. There's a configuration option in Google Desktop that lets you indicate that you're more interested in launching programs than finding stuff. This turns Google Desktop into a fantastic program launcher, particularly for those not-used-so-often-have-to-search-for-programs that one tends to ding into the Start Menu looking for. Since I've incorporated GDS into my productively cycle as an augmentation to SlickRun I've not needed the start menu.
A while back, after I got my Mac, I (mentally) declared QuickSilver to be the greatest program launcher ever. Anyone who gets QuickSilver done right on Windows, they will have a license to print money.
Colibri is a pretty decent start at a QuickSilver for Windows. Just like QuickSilver, you hit Ctrl-Space and start typing.
The documentation is weak, but if you do a little digging you'll figure out that sometimes you need to press TAB and sometimes you need to press SPACE or ENTER to get what you're looking for.
It's about 20% of the way to being QuickSilver, but it's a great start. I hope the author keeps development up and moves it forward.
Other apps to try out in the same vein are, of course, SlickRun, but also AppRocket, ActiveWords, and Launchy. I talked about these in my Hanselminutes Podcast #15 on Replacing Start|Run.