SpotLook is a graphical interface to Mac OS X Leopard's Spotlight desktop search engine.
It features tracks, which are timelines showing results according to their date.
Tracks can be created, edited and customized include a search scope and attributes to search for.
Found items can be viewed with Quick Look or revealed in the Finder.
This is an 2500 Objective-C lines open-source project; your contributions are welcome.