USB-powered desktop gadgets can be fun and sometimes useful, but they're often priced at not-so-fun prices. Learn how to splice a USB cable to power simple gadgets with MaximumPC's guide.
The USB splicing tutorial is actually just one part of a single hack from their "Nine Kick-Ass DIY Projects", but it's a nice primer for anyone who's never been up for cutting open their own spare cables. Once you've pinned down how to splice, connect and ground your connections, you can power up just about any low-power device you have laying around, like fans, coffee warmers, toys, lights or whatever else you'd like.
You'll definitely want to read through for MaximumPC's cautions, and maybe Google the project you're attempting to see if others warn against it, but this looks like a photo-friendly project waiting to happen. If you've already done it, in fact, we'd love to see the results in the comments.