ENELOOPS: If you haven’t discovered these wonderful rechargeable batteries, you are in for a TREAT. Unlike conventional’ rechargeables they maintain their charge almost indefinitely. The batteries are low self-discharge NiMH, which lose their charge much more slowly than ordinary NiMH batteries; 10% in the first year, compared to about 4% of their charge per day of storage (for conventionals). Some of these little guys can be recharged up to 3000 times! Sanyo also have a nifty fast charger which recharges four AA/AAAs in a few minutes. All used to be available at Dick Smith stores: http://en.wikipedia.org/wiki/Eneloop
PS: They now have a black version which is heavier duty but does not recharge quite so many times. I have used both zillions of times and find them absolutely great. Also top wattage per gram.