Launchy
What is it?
Source/Link:
Launchy: The Open Source Keystroke Launcher for Windows

What is it?
How does it work?Launchy is a free windows utility designed to help you forget about your start menu, the icons on your desktop, and even your file manager. Launchy indexes the programs in your start menu and can launch your documents, project files, folders, and bookmarks with just a few keystrokes!
What can it launch?Once Launchy has been started, it hides in the background. You bring it forward by holding the alt key and tapping the space key. You then type in a few keys of the program you are searching for and hit enter once it has been found. You can also make Launchy disappear again by hitting escape or alt+space.
It can launch whatever you index. It can be your documents, mp3, bookmarks etc etc. For e.g. If you want to listen to a particular song, you no longer have to open your music application and then search for the song. Just press [Alt] + [Space] (or your assigned key) from anywhere and type the song and wow!!!

Source/Link:
Launchy: The Open Source Keystroke Launcher for Windows