One of the best investments I have made thus far is a Duracell battery charger! My model came with two AA rechargeable batteries but you can get different models that hold more and/or other sizes.
Not only does it look cool and comes in bright colours, but it is so handy to use, and EASY! It's like a littlle pod, the plug folds up and down and the green light tells you when it's done charging! It fits in a purse or backpack for those vacations when the kids have their handheld games to keep them busy and the adults are taking loads of pictures! I highly recommend it!
Here's some pics!