On my Android phone, however, I use the "desktop" exclusively to find what I need. Maybe transitioning desktop UI's to something similar is a great move.
Apart from that, the background is just used to show pictures. It's surprisingly awkward with multiple monitors: I had to write a program that composed the pictures I wanted to display, then set that new picture as a tiled background. If you don't do that correctly, and you have multiple monitors with different resolutions, you end up with either the same image on all monitors, or clipped / stretched / distorted versions on all but the "home" monitor (the one that owns (0,0)).
It's the best thing since sliced bread for Windows, I've been using it for a couple of years now and can't go back. Just hit alt-space, enter few letters and launch. Just like Awesomebar but for launching apps. It indexes all files if you want and it's quick as snap.
Apparently it's also available for Mac and Linux.