Well this is rather nifty. A company called Blaze has developed a case for the Nintendo DS that lets you select from three different games, just by flipping a switch. It's a neat solution to the problem of having to carry around loads of those tiny cartridges.
A ribbon connector plugs into the slot that games normally go into, and your games are then inserted into one of the gadget's three slots. You select which you want to play with a switch, and a green LED indicates which is active at any one time.
Although it's not the prettiest unit in the world, it's undoubtedly useful. It's cheap too. $13 - which works out at about 8 quid at current exchange rates. It's coming from Hong Kong, so be prepared to add some shipping charges to that.