I like to promote products that we find to be very useful or particularly good value for money. On Ladybug I we used a lot of AA batteries for things like flashlights, clocks, and the SSB receiver. I found that the performance of NiMH batteries was good for a while, but they rapidly became useless because they would not hold a charge for any sort of reasonable storage period. This was a huge issue with the Pentax digital SLR that I had deliberately purchased because it used AA batteries (and was also water sealed). In researching the problem with this camera, I came across a post on a forum about a new technology that had been applied to NiMH rechargeable batteries by Sanyo that apparently cured the problem of rapid discharge during storage.
I bought a set of these Eneloop 'pre-charged' batteries and have only had to recharge them a couple of times in 2+ years of use in the Pentax SLR (which admittedly gets very light use). I recently bought more of these batteries, some from Duracell (apparently rebranded Sanyos) and have found that they work very well in the handheld GPS and in flashlights and head lamps. Highly recommended - we will be recycling our regular NiMH batteries or using them in very low drain devices like clocks.
You can buy these batteries at Canadian Tire or MEC in Canada. Just make sure the package says "pre-charged" or something to that effect. They cost about $15-$20 for 4 AA batteries.