I use Eneloop batteries. They're great as they have very little idle discharge, so you can leave them on the shelf for months and they're still good to go when you need them.
One more for Eneloop.
Just avoid "lite" versions, these are not for intensive use.
Emil Pozar, http://emil-pozar.photoshelter.com/
|Meet at HKCC Rain or Shine by pen araneae|
from Your City - Rain Down on Me
|Pregnancy Is Beautiful by sye46|
from Women's World
|Criss-Cross Traffic by PEB|
from Best Use of Motion
|Picking a Star in the Milky Way by vbuhay|
from My Best Photo of the Week