BatMax is a wafer-thin product that promises to dramatically extend the life of rechargeable batteries, while simultaneously decreasing the amount of time it takes to recharge them. How exactly does it do this? Well, you know, nanoceramics... patented IonXR technology... blah, blah, blah. Basically, to me it sounds like a tinfoil sticker that does nothing at all but lighten your wallet a bit. Though maybe it really does work. What do I know. However, I see that the folks over at Gizmodo and Slashdot are skeptical as well.
Update: Some guy tested whether battery extenders really work, and found that they did extend the life of batteries by about 10-15%. So maybe there is something to this nanoceramics thing.