A GPS navigational device isn't going to do you much good when the batteries run out. Designed with the outdoor adventurer in mind, this Transystem i-Blue757 Solar GPS Receiver [product page] features a compact clamshell design that fits easily into the pocket. The bottom half of the shell features the solar panel, and the GPS antenna is embedded in the top portion. The device runs for 30 hours on a rechargeable Li-Ion battery, and solar power will keep it running for an additional 100 hours. To cap it all off, the device supports Bluetooth, so you can sync it with your PDA (if it's not out of juice before this thing is). Via