Can you believe that some batteries are made up of... guess what... other smaller batteries?
No neither could I. Whilst I suppose it sort of makes sense, its sort of a cheat, isn't it? Also as the geek in this video points out the smaller batteries retail for way more than the cost of the larger containing battery.
12 Volt Battery Hack! You'll Be Surprised... - video powered by Metacafe
Ahh, I can still remember licking the top of a 9V battery (having been dared to do so) and shrieking in surprise.