If you are reading this you are interested in replacing your many AA or AAA domestic batteries with rechargeable's.
Traditionally the issues which cause people to resist making the change are:
a) Self Discharge where the rechargeables loose their charge very quickly even when just being stored.
b) When you take them from their packaging when new they need to be charged up overnight.
The answer to both related problems are the new "low self discharge" batteries that many manufacturers are releasing, the most advanced are Eneloop by Sanyo.
They were amongst the first with the new battery technology, and have stretched their lead further with their second generation Eneloops, which work better than uniross Hybrio or Duracell Staycharged offerings.
Though these batteries appear to offer a lower capacity at 2000mAh than other high capacity traditional rechargeable's, in fact for many use cases they offer superior real world performance, since they hold their charge. The one exception to that rule is if you are using the cells immediately after charging in high drain devices, like an older digital camera. In which case perhaps a higher mAh traditional tech cell may be more appropriate to the task.
The new second generation Eneloops claim to retain 75% of their charge after 3 years if lefy unused, so could still be taken out and employed usefully after being stored. Try that with traditional rechargebles and they would most likely be completely flat!! This means that Eneloops can be used in a world of low drain devices like remotes or clocks or torches in the car glovebox for which traditional rechargable's have been most unsuited, since they self discharged relatively quickly.
Eneloops can appear quite expensive initially compared to alkaline or cheap NiMH cells, but their value soon becomes apparent.
Incidentally it still seems that both first and second generation eneloops are being sold at the same time - the way to spot the difference in the packs is on the top left hand side the second gens say "upto 1500 times" while first gens say "upto 1000 times".