I wasn't able to figure out how to remove the top and bottom panels (the window list thing at the bottom and the shutdown button thing on top).

I like vertical real estate (would like to merge them into one, like I could with Ubuntu 10.10). And I like no toolbars on on top (to make it easier to click on my firefox tabs (see below)).

My favorite GUI customization is to remove the "decorations" (window frame, title bar etc) of maximized windows (to get a little more vertical space). This also makes firefox's "tabs on top" feature look the same on Linux and Windows.

You can do it with Compiz+XFCE (which I did in 10.10). Compiz isn't working for me under XFCE in 12.04, so I'm using a PyGTK script I found on the Net to do this.