I suppose it's the nature of a napkin sketch to be a last-minute endeavor. That said, if you were thinking about entering our sketchy contest, time is nearly up. Entries need to be posted in the contest thread by 11:59 PM CT tomorrow night. When we announce the winners next week, we'll find out if my fake review of a fuzzy computer case actually convinces someone to choose it over more conventional options.
If you're, uh, drawing a blank, here's some advice. When it comes to zany PC-related inventions, just look around your desk and ask yourself, "how can I make one of the devices I'm staring at less practical?" I've posted one of my ideas above to help get your creative juices flowing and to assure you that you don't need artistic talent to enter. It's a trackball, but it also has an optical sensor on the bottom so you can use it like a mouse. You can set the sensitivity of the ball separate from the main sensor and sell it as an ultra-precision input device by adding the maximum DPI values together. I'm fairly certain that's a legitimate marketing strategy.
Now get sketching and share your own cockamamie contraption with the rest of us before it's too late.