Launchy is a free and open-source muti-platform application launcher.

RecentX is a launcher for Windows designed to make your computing life joyful.

Keypirinha is a fast launcher for keyboard ninjas on Windows.

Ubiquity is an extension that allows for the use of dynamic commands in Firefox.

Find and Run Robot (FARR) is a program for keyboard maniacs -- it uses an adaptive "live search" function to rapidly find programs and documents.

Executor a multi purpose launcher and windows run replacement.

Enso Launcher is designed to give you instant access to your applications and windows.

SlickRun is a free floating command line utility for Windows. SlickRun gives you almost instant access to any program or website.