I found an ugly kid joe CD in my couch...never heard of the band until then.
My friend who works at a strip club(front desk guy) found a really nice camera phone in the lost and found, on it was a video of a pretty good looking girl...erm...orally servicing the previous owner. It was deactivated so he now uses it.
Also you should probably post a notice in the apartment lobby or somewhere where other residents can see that you found the disk. It probably belongs to someone in the building.