I want to thank whoever it was (in a long thread some months back) who put me on to Eneloop batteries. They are great--definitely last longer than alkaline batteries. They also, of course, keep used-up batteries out of the landfills.

My problem was specifically my camera, a Canon A710, which was eating batteries like there's no tomorrow--I could use up a set of alkalines in a day. Per the instruction book and the Canon website, lithium batteries are a no-no for this camera. I have solved the problem--there is a power-saver feature on the camera so I can turn off the LED screen and use the viewfinder. Of course I've had to make some adjustments for parallax and for the fact that what the viewfinder shows is a little smaller than the actual picture (I've had to use software editing tools more). But with the LED screen turned off and freshly charged Eneloop batteries, I went through a 7-day trip, taking LOTS of pictures, with only one set of batteries.

However, the spare Eneloop batteries I took (and didn't need) required about 6 hours to recharge after being exposed to temperatures close to freezing without any insulation. I suggest keeping the camera (or whatever you're using the Eneloops in) and extra batteries well wrapped up inside your pack at night.