I recently had my camera die on a road-trip, and only had my cel phone and charger -- turns out their worlds aren't so far distant!
Checking the voltage and polarity to be correct, I taped the camera battery into my phone, and lo-and-behold, it booted up! Add a little juice, and you have yourself a charged battery! I used this technique to charge the fully dead battery pictured in the video to about 75% so it had plenty of juice to shoot ALL the pictures and video from my other instructable!
This is not a permanent solution. It's a one-off setup for when you're really screwed in the middle of nowhere. I make no claim to your ability to replicate the results I've had, but I do feel it's likely people with similar situations will be able to do similarly with similar equipment.
******ALWAYS MONITOR A JURY-RIGGED CONTRAPTION LIKE THIS WHILE CHARGING. IMPROPERLY CHARGED LITHIUMS DONT JUST FAIL, THEY FAIL SPECTACULARLY. USE APPROPRIATE PRECAUTIONS, AND DON'T CRY TO ME IF YOUR PHONE 'ASPLODES'. YOU HAVE BEEN WARNED!******