that would work if the police participated. around here its a mix. in oregon they hold on to stuff for a while and if no one claims it then they put it up for auction, at the auction you also have a chance to prove that it's yours, or you can bid on it. there's also places like www.stealitback.com
for nationwide auctions. but in Washington it seems different, my dad works for city bus transit, and every month they have lots of recovered bikes that are left on their busses and whatnot, they try to turn them over to the police who say they're so busy and overloaded they might as well take them to the dump. i dunno what they actually do with them, my dad says some of them are nice bikes, but he won't let me take any as he still thinks its stealing. i was thinking of doing my own "vendetta recovery" project, like try to pick all bikes worth more than $300, you know, bikes people would miss, and take pictures post flyers and craigslist listings and see if i can reunite people with their bikes. or at least turn them over to a co-op or something that has better resources for that kind of thing.
or for a measly $60,000 a year i'll take a job with the police's recovered items department and post my own fliers and listings to recover stuff for people. i'd imagine it must be hard to link people to things, i have lots of nice toys and i don't have records of serial numbers to any of it, i usually just hold on to that stuff for 30 days or so and shred it. I do have records for my car and my bike though.