affinity-search - Google Code
Affinty is a desktop search tool, which hopes to provide a quick way to get at all the different information on your desktop. It achieves this by having various back-ends, but implemented through one standard interface. Speaking of the interface, have a look:
Yeah, if I forgot to mention, Affinity is RGBA-aware, so it not only does it do its job well, it look good doing it :).