I've visited this website and found out theres heaps of amazing casemods. Though this isn't what we call a gadget, but homemade stuffs are way better than industrial made items. There's a couple of real life dolls made into PC cases, to tiny little Atari like machines. Click here to view them.
Well, floppy disks were previously known to store data, but now retailer American Science & Surplus makes the disks useful again. The Mock-Floppy Brush is a floppy disk with a 2-1/2" long row of anti-static nylon brushes on the end of it. You can dust your computer and around it. It comes in colors of lime, tangerine or grape and sells for $1.95 each.