Google Quick Search Box
I've recently decided to retire the excellent but slightly flakey app launcher extraudinaire and more Quicksilver (which has now gone open source) in favour of the new beta and slightly less capable Google Quick Search Box.

Google Quick Search Box (Flickr)
I say "slightly less capable" however it really is early days, it seems to be fully set up for plugins and was created by Nicholas Jitkoff and Dave MacLachlan, Jitkoff was actually the man responsible for Quicksilver.
So far it seems to be going well, it has a clean, clear and simple interface. Preferences allow changing the colour of the box around the search, what you search and linking to a Google account (though it doesn't yet search Gmail) and a few other tweaks. My only complaint so far is that the default trigger short cut of double-taping the Command (⌘) key can sometimes invoke GQSB when you dont want to, so I have set it to my Quicksilver short cut of Ctrl-Esc.
If you're a light Quicksivler user give it a go, if you're a heavy user keep an eye on it.