Picked one of these up yesterday. A good device to keep in your car to power a variety of mains powered devices.
Retailing at around 30-40 pounds in other stores.
Example : http://www.maplin.co.uk/Module.aspx?ModuleNo=97788&criteria=car%20power%20inverter&doy=25m2
USB charging point, ideal for charging your iPod
Brushed-aluminium finish with soft-touch trim
Slots into your car cup holder
DC plug includes a spring tension switch to allow for safe, secure connection for different sized sockets
Coiled DC lead for convenient storage
Overload and temperature protection