Those with cameras, flashes, and other accessories that use AA batteries often wished that AA batteries behaved like LiIon batteries in that they did not lose their charge over time. The manufacturers were apparently listening because now a number of them have introduced rechargeable AA and AAA batteries that retain their charge over a long period of time.
Now if you completely drain and recharge your batteries on a daily basis you are probably not going to get any benefit from these, but if you don't want or like to recharge everyday and you don't drain the batteries on a daily basis, these may be for you. You can also use these as your backup instead of single-use disposable lithium or alkaline AA/AAAs.
So let's meet some of them. First up, we have the Sanyo Eneloops which are probably the most famous name among the group. The AA batteries are rated at 2000mah and and the AAA are at 800mah. GE/Sanyo make two charges, one four-battery and one compact two-battery charger.
Next up we have the Mizco Digipower Endure BHNDR2AA that come in a 4-pack and are rated at 2000mah as well. They are ready to use out of the box and can survive up to 1000 recharges. Also joining the low discharge NiMH party is Sony with Sony Cycle Energy batteries in AA or AAA format. Sony claims that their batteries retain 85% of their charge after one year.
Uniross Hybrios by Ultralast are another option as they are rated at 2100 mah. Their AAAs are rated at 900mah. Just like the others, they are ready to use out of the box and can retain their charge over a long time.
And now let's look at the Rayovac Hybrid batteries. Rayovac's energy retaining AAs are rated at 2100mah, and claim to retain 80% of their juice over a year. They are available in AA and AAA, and they also come bundled with a charger, but one of the Amazon review mentioned that this is a generic non-smart charger, so it's probably a good idea to use (or get) a smart charger, that way you make the most of your batteries.
Uodate 9/18/07: Added Rayovac hybrid batteries as well.