Registering your stuff free, for easier recovery
You can register make, model, serial number and photos of some of your portable possessions online (laptops / notebook computers / UMPCs, PDAs, mobile phones etc) in order to help get them back if they're recovered after being stolen or lost.
I'd previously covered MendUK (now called Immobilise or the Immobilise National Property Register); it's recently been revamped so I thought this was worth a reminder. As they put it, "it's supported by all the UK Police forces, the Greater London Authority, Transport for London and The Mobile Phone Industry".
They also have a division in the USA, called appropriately Immobilize.
It's free to create an account and register your mobile property with Immobilise, but you can also buy their wares e.g. tracer tags and property markers for bikes, luggage etc.
Immobilise is accessible from a police database, the National Mobile Property Register, so that police officers can search for items by serial number and check who they're registered to - and trace the real owners to return them to. Of course, note that this also means that, as the site puts it, as a registered user of Immobilise you'd "make your property ownership details viewable to the police".
The Immobilise register is also checked by lost property offices like the Transport for London Lost Property Office (where incidentally you can enquire about stuff left in black cab taxis as well as the Tube, bus, DLR or train, tram etc).
Is it legit - or stolen?
Before you buy something secondhand from eBay or elsewhere, particularly electronic items like games, stereos, satnavs etc, it might also be a good idea also to check if what you intend to buy is legitimate.
Generally, while the law differs in different countries (so you should check the position in your own country), a buyer of stolen goods is not allowed to keep them even if the buyer was innocent and genuinely didn't know or have any reason to think that the things they bought were stolen.
So you could be out of pocket if stolen goods are traced to you - you've lost money that you paid the thief (who's probably long gone by the time the authorities come round), and you also have to give up what you thought you'd bought.
However, it charges people a fee (or subscription) to check the history of items registered on their databases: currently £1.99, €2.50, or US or Malaysian $2.99.
I'd have thought people would be more willing to pay a fee to register their stuff, than to pay to check the serial number of something they've just paid for and then find that it's taken away from them because CheckMEND search results showed the item was on their register as stolen, and they reported the search to the police!
(See Checkmend's UK Conditions 21: "...We can be compelled to disclose this data to the Police or other authorised bodies for the purpose of investigating or preventing a crime. In order to protect those making CheckMEND checks and owners, when requesting a CheckMEND on the Website, via SMS or by email you agree to our supplying data to the police or other law enforcement authorities for the express purposes of the prevention and detection of crime, arrest and prosecution of offenders or for the recovery of stolen property.")