Ars Technica posted a guide showing how to make a laptop sleeve out of any fabric you happen to have lying around. It probably won't protect your laptop from falls, but it'll provide some style and probably reduce scratches.
Unfortunately, it does seem to require some basic sewing knowledge—that's a problem for me, since my greatest sewing accomplishment is basically strapping a button to my coat with about half a spool of the wrong colored thread (and it still falls off every couple weeks). But if you're a real human being with basic skills (which I clearly am not), it should be a pretty simple project, and a nice way to customize and protect your laptop at the same time. [Ars Technica]