This All in One SIM Card enables you to put all your mobile numbers on one sim card. Eliminating the need for those unreliable dual sim card holders and meaning you'll never have to remove your battery again. It lets you have 12 providers and phone numbers on one card, and also lets you change number without turning the phone off.

Total cost is $42 for the reader/writer and $27 for a blank sim card, which is about £40. tI have no idea how this works, but they're available from http://mobile.brando.com.hk/