SendMeHome is a new and free lost and found database. It works by having users register their personal effects with little stickers that have special "phone home" codes on them. If someone finds something you've lost with one of these codes on there they can plug it into the service and get whatever contact information you've left--hopefully bringing you and your lost iPod (or whatever) back together.
Similar programs for bicycles have existed for years, and there is definitely a rate of return, although it obviously depends on what you lost and who has found it. SendMeHome's entire system relies around the stickers, which you can either print out with your own materials or custom order from the service for a small fee. These packs run anywhere from $3, all the way to $17, which includes 60 various sizes you can stick on all your stuff then write the codes on with a permanent marker.
The service is being promoted as a good way to get textbooks back, which in a college campus could be downright worthwhile. Things like personal electronics and valuables are clearly less likely to be returned. One thing that is really nice either way is that it's completely free to register items with the database, so whatever is added will remain there "for life."