My dock there was kiba-dock. You can get the .deb file here:
http://www.forestofthought.com/Other/kiba-dock_0.1-1.2_i386.debOtherwise, find it yourself. To add stuff to it, you need to put launchers in you .kiba folder somewhere... tell me if you need more help with that. Kiba is cool because it has a physics engine built in. The icons can bounce all over the screen in crazy ways...
(Oh, and you need a composting manager running (such as beryl or compiz) to make it transparent)
Currently, though, I'm using Avant Window Navigator. Seriously awesome. I think it'll get into Gnome for Gnome Topaz. Here is what the current AWN can look like... (very customizable).

Note, yes, I know about quicksilver. We have something like that for Linux, but I've forgotten what it is and I don't use it. Probably not as good.