i hate the taskbar more than anything else in life...well, maybe not that much, but i could do with a better alternative. i want something like the desktop, where i can move things around the screen and group things as i see fit. i'm very visual and want things spaced out, not in little tabs. i want to hit alt-tab and have all those things pop up real nice-like. i'd even be happy with something that would be similar to firefox tabs, custumizable and such
http://rocketdock.com/
RKlauncher is similar
http://home.cogeco.ca/~rklauncher/
If you have XP and want similar taskbar features to Vista, you can try Visual tasktips and Shock Aero 3D - both free
http://www.visualtasktips.com/
http://update.docs.kr/entry/Download-Shock-Aero3D-en
The only other thing I can think of is Xneat which adds some features to the taskbar such as shuffle tabs, transparency and minimizing to the system tray; free here
http://www.xneat.com/windows-manager/
If the taskbar gets cluttered with quick launch items, you can drag the Quick Launch toolbar (first uncheck "Lock toolbar") to make a window or a new taskbar. You can do that with any toolbar.
The original taskbar is special, in that the Start Button, the tasks, and the Status Bar (the one with the clock) must stay on it.
Quick Launch items are shortcuts stored in a folder like C:\Documents and Settings\<user_name>\Application Data\Internet Explorer\Quick Launch\ . The Application Data folder is hidden by default.
Hope you find some of this useful!
Now, I just would like to say that I would also like a Taskbar replacement. The taskbar is part of Windows Explorer (explorer.exe). So, if something (copying a file, for instance), make Explorer unresponsive, the Taskbar, including the Start Button and the tasks, does not respond either. The option would be to Control-Alt-Delete, use Task Manager to kill explorer.exe, and, if necessary, click "Run" and type "explorer".
Update: I just checked out RocketDock (first answer). I can tell it basically cloned the Mac OS X Dock, but it looks so cool anyway.