I've thought about a platform that collects speeds of vehicles and then publishes a database of speeds matched to license plates as an open data set. Police would likely not touch it, but a large enough database might be a tantalizing prize for automobile insurance companies. And then my desire for more disincentives for speeding runs afoul of my feelings about dragnet surveillance, and so I abandon it.
In terms of having the potential to effect direct action against speeders, I don't know how effective simply monitoring speeds would be. That said, some cities (such as Seattle) will lend speed profiling equipment to community groups in order to establish whether or not a given segment of road might be a candidate for traffic calming: http://www.seattle.gov/transportation/ntcp_calming.htm