The Mobile Weather Station

Rig up a portable computer (netbook, laptop, 42-pound desktop with backpack straps and a solar panel), a mobile Internet access method (tethering to a phone, getting one of those USB wireless modems, 50 pringle cans taped together and aimed at the Moon), and an array of meteorological sensors (bluetooth thermometers, USB barometers, one of these mounted to a cheesehead hat). Set it all up to publish up-to-the-minute weather reports to the Internet about wherever you are. Run tits-first into either a major storm or an art museum. Record data for science.