This Ars Technica review contains a nice survey of Dock substitutes and other launch utilities.

Most interesting is the stuff about Quicksilver, which is a really interesting utility that Josh pointed out to me a while ago. Whilst I was working at SI I had it installed on my G5, and it really started growing on me. For a long time I didn’t have it on my laptop, so I’m only just starting to get into it again. It’s pretty good though - kind of like a graphical command line (but much better than that might sound!) :)