Namely - app keyboard launcher

Namely is a very small (200k) app that works in a very simple manner: you set up a hotkey (in my case, option+space) and its window appears. You type the first letters of any app and it shows a list of results, besides learning your habits, i.e, if you type 'fi' and Firefox appears down the list, just select it and the next time you type it, Firefox will be the first on the list, so you just have to type 'fi' and then Enter.

For app-launching purposes only, it's much faster than the powerhouse app Quicksilver, which still deserves a VERY long post since you can do almost anything imaginable with it.