A few years ago, Microsoft Research wrote Task Gallery, a well thought out 3D window manager. I have always thought it was great...it's a shame that it doesn't look like it'll be a part of Vista.
Also, someone mentioned being able to move taskbar buttons. Well, do a google search for GroupBar. MS Research also made a 'taskbar' that does that, but goes a step further and lets you group windows into tasks via the taskbar. Actually, that one you can even
download free from MSR.
It seems like the research folks are making great interfaces, but that the development groups are either unaware of their work, or they just don't care!