HandymanWire - Wiring outlet types
This should help you figure out what type of outlet you're looking at. FYI: In alot of older homes they only used 50 amp plugs/wiring, and put a 30 amp fuse/breaker in when 30 amps was all that was needed. In our case, our dryer had was on a 50 amp circuit with 50 amp plugs, but a 30 amp fuse because that is all the dryer pulls. Confused the living hell out of the delivery guy when we got a new dryer.
As for turning it into something useful, it's probably a 220, rather than 110, which is your standard wall outlet so you can't just swap out the outlet. Try
this if your feeling brave. I would strongly recommend against doing this alone if you've never done it before, it's absurdly easy to kill yourself.