For a brief time at my last job I switched to OS X. One thing it had that was very cool was the dock, a combination of customized quickstart buttons for your favorite apps as well as a system tray where apps went when you minimized them. The windows task bar is really nothing but the latter - it'll tell you what's open, but it doesn't give you the chance to open new things.
RocketDock, linked above, is exactly that and it's very good at what it does. Create yourself a dock, put the apps on it that you need, and you're good to go. Perfect example of good software. Small, light, and very good at what it does. If I could get the task bar to just go away completely, I don't think I'd miss it.