I lost my wallet on a street sweeping day so I called 311 to see if they may have picked it up. They were able to get me in touch with sanitation, which was able to tell me the chief of the truck that does my block, who answered on the first call and said he'd talk to the guys to see if anyone found a wallet. There are times when 311 has failed me but this time felt like magic even though they did not find my wallet (a good samaritan neighbor did).