CNet has an article this morning about a company named ParkingTicket.com that makes money by helping you fight parking tickets.

And, if you can't fight it, they at least let you pay it online (in many jurisdictions).

The service automatically generates dismissal letters for you and then you can send them off to the local jurisdiction and see if you are lucky. There's not any particular gimmick, just an expert system trained in the laws of many jurisdictions that helps you determine if you really should have gotten the ticket in the first place.