Google Quick Search Box
This stand alone app ties into the Spotlight search feature of OS X and displays search results from across your computer and the web.
It’s fast and easy to use with a very clean interface.
Once you begin typing your query, a list of matching results appear and you can perform actions like playing the song or launching an app. You can dig deeper into your local results by using the right keyboard arrow (it even shows your hidden files which is pretty slick.)
After a morning of use, I already prefer this app to Leopard’s built-in Spotlight search.
Google Quick Search Box is worth a look. It’s a free 4.5MB download from Google.