This is probably one of the coolest applications/plugin I have installed on my Mac. It brings out a Quake-like console that comes down from the top of your screen. Talking about convenience! I never liked the Widget Term – takes forever to load. And the Terminal.app just adds more clutter to my screen real estate.
You can download Visor here: http://code.google.com/p/blacktree-visor/
It is free and it is from Blacktree – the creator of Quicksilver, another very cool application for the Mac.