The folks at HowToGeek have put together a pretty comprehensive compilation of docks and other launchers. Personally, I am a bit stodgy about desktop stuff. I have tried docks before and while they are pretty snazzy, I always seem to uninstall them after a few days. I confess that regardless of whether I am using Windows or Linux, I tend to fall back on the "start-button-and-nested-menu" type of interface.
I was not too enamored of Ubuntu's recent Unity desktop, and Windows 8 Metro leaves me pretty cold too. It may be because I am not a "power user" in the true sense, and I typically don't have huge numbers of programs installed at once. About the only customization that I regularly use at work is a "virtual screen" utility that gives me three desktops on one monitor - that definitely does help me organize stuff.