There is a belt that goes around the part that holds the clothes and makes it spin. It is possible that this belt has broken or slipped off.
The electrical motor that spins the belt could also be shot. If you know someone who is mechanically inclined, dryers are pretty simple to work with and in a lot of cases, especially if it is still getting hot, it is cheaper to fix them than buy a new one.
However, if you have to hire someone, this can get pretty pricey, so I would recommend checking the price of a new dryer and calling a few dryer repairers to find out their price. You can then compare the two costs.
If you live in the States, you can often find a worker on craigslist that is pretty cheap.
If you do decide to service it yourself, make sure that you unplug it from the wall before doing any work!