Meta is a desktop search tool that combines an extended and improved version of the familiar Spotlight query language with a multi-window interface. Features include:

Search terms can be combined using "and" and "or" boolean operators (think "movies or music" to find all your movies and music)

Searches can be restricted to specific folders, so you can focus your searches much better than in Spotlight, which looks everywhere

Spotlight comments can be edited or appended for multiple items at a time, which makes Spotlight tagging really easy