Hongkong based gadget shop Brando sells a compact cartridge that gives your FM radio on your Nintendo DS.

This DS accessory uses the LCD screen of the game console to display the user interface for changing frequencies. It is powered via the DS and supports a frequency range of 87.5-108MHz. You can buy the Radio for the Nintendo DS on Brando for $14.

FM radio is a great way to listen to music and using only consume little power from your batteries. I am actually finding myself using the radio feature of my Nokia N80 quite often. So if you anyway roll with your Nintendo DS Lite in your bag, why not make it a radio too?