If you need a good battery charger, get this one. It is easy to use and has an indicator that tells you when the battery already is charged fully or is defective. It has four different charging speeds, and best of all, you can recharge four AAA or AA batteries. I recommend it because I use it. I think it's great for keeping the flash or other AA equipment running smoothly.
La Crosse Technology BC-700 Alpha Power Battery Charger
If you also need AA batteries get the Powerex AA 2700 they are more powerful and last months longer then regular AA disposable batteries, since they are rechargeable you can have them go for years before needing a new replacement.
Powerex AA 2700mAh NiMH Rechargeable Batteries w/holder- 4 Batteries Per Pack