Being the former RadioShack employee that I am, nerdy hacks of any sort are always a big hit with me. These videos were definitely interesting to the nerdy part of my soul. Enjoy!
6V Battery Hack
As fascinating as the above video is, a word of caution. Usually the cheaper 6V batteries have these awkward D-battery-ish monstrosities. The following illustrates what you can do with those suckers.