Or you could always just make Konsole transparent, and maximize it. And doesn't XFce have a command-line field that can be added to the panel?
I was just looking at Ion the other day, though, and it does look cool.
http://modeemi.cs.tut.fi/~tuomov/ion/
A lot of people seem to do that sort of thing with blackbox and fluxbox as well, but I don't know how (yet).