[DXL]

Launchy is a similar app for Windows and Linux. It's not super great for finding and opening files, but it's a great timesaver for opening websites and applications, especially if you use your keyboard more than your muse (as I presume most hackers do).

http://www.launchy.net/

[Plugawy]

Interesting thing is that the latest version of Launchy works on OSX as well.

[ctingom]

I use it to index my folders so I can get to them fast.