Non-Linux FOSS: Launchy!
With Unity's method for launching and finding programs and applications, and OS X's spotlight tool becoming the new way to launch programs, the entire way we think about launching programs is changing. Although I still like to have a few icon shortcuts on my task bar, many folks prefer a quick keystroke to bring up Gnome-Do, or Unity's launcher, or even OS X's spotlight. If you're one of those people, but can't seem to find a smooth way to accomplish your launching on Windows, check out Launchy.
Launchy is an open-source dæmon that runs on Windows, OS X or Linux. It listens for a predefined keystroke and then pops up a search window. You start typing the application, document or media file you want to start, and Launchy autocompletes based on its index of your system. The main advantage is the ability to launch a program without moving your fingers from the keyboard.
(Image from http://www.launchy.net)
Launchy is fast, accurate and doesn't steal lots of resources on your system. I can't find a way to make Windows behave this way on its own, so although Launchy is cross-platform, it probably will be the most useful for Windows users. You can download your copy today at http://www.launchy.net.