There's lots of privately owned parking out there, even around airports, but nor market for it. What about a web market?
Imagine, if you owned a parking space, you could file it in a database. People going somewhere hard or expensive to park would go to the web before the trip, enter the address, and get offered a spot near their target with a rate. This could also include commercial lots with spare space. If not at the web, you could call from your registered cell phone for a small extra fee while driving to your destination.