A regular bathroom vent fan can be installed much like it would be on a main floor. The difference being that instead of venting out the roof, a hole is drilled through the joist band where the vent exits the basement out the side of the house just above the foundation. In most cases this is a relatively simple installation. (The same method is used to vent a clothes dryer in a basement).
You don't realize the value of a window until you don't have one.