Brian Mastbrook describes very nicely how Quicksilver combines the best of keyboard-driven interfaces and graphical interfaces. Unfortunately, QuickSilver only runs on 10.3 and later, which is why I'm still stuck with LaunchPad - which, however, in the latest versions (aside from the really extremely slow startup) can keep up quite well.
In general, I find this slowly developing idea of combining graphical and keyboard-driven interfaces very pleasant. Graphical interfaces are good at presenting complex structures (a directory structure becomes clear to me graphically faster than from the shell), but they are often quite cumbersome to use. Tools like QuickSilver and LaunchPad help tremendously. Apple's Universal Key Access would probably help me too - if I had 10.3...