Jo, a longtime Internet friend of mine, sent me this link. I don't even drive, so it's of no use to me. But Cliff might be interested. And I'm sure a certain pesky brother-in-law of mine who now lives in St. Louis can use the information it provides.
Just click on: Speedtrap exchange.
You can even submit speedtrap locations to the site yourself, or comment on the ones that are already there.