Unknowingly, I had dropped my wallet in a cab late at night last summer while getting out to make a dash for cover in pouring rain at the HKCC parking. Only HKD 60 or so in there but lots of cards - cc's, ATM cards (local and overseas), Perm HKID, driver's licences, social insurance, citizenship, loyalty clubs, etc. And this just a month before moving from HK - the last thing I needed. Called the cab lost and found number (searching Geoexpat threads), finally decided not to pay for the broadcast because of the very limited service they offered and the shift change that had just happened. Started the cc/atm/hkid card cancellation and replacement process and next morning made a police report at the Happy Valley station where they keyed everything into a database.
Five days later got a call from Citibank (credit cards) to say that my wallet had been turned in at xyz police station.
Apparently, cop stations have a bin outside which people can drop found stuff into anonymously.
The wallet was wet from the rainwater in the bin and everything was intact except the money, which the cabbie must have taken (small price to pay) and the HKID card which the cop station had taken and cancelled. It must have been the cabbie who dropped it there - the location of the copstation where cabs line up to go into Shun Tak Centre suggests that. Interestingly, I don't think the police looked at all at the database to link up with the police report I had filed at - otherwise, they might have called me on my cellphone. Instead they called my local credit card bank (Citi) to pass on the message.
Anyway, it saved me a huge lot of bother - esp Canadian citizenship card, SIN, driver's licence, all of which I was still mulling what to do about, and the loyalty cards. The cc/atm replacement process was irreversible once begun.