While
mblase has raised some excellent ideas for saving batteries in your digital camera, I think emphasis must also be made on the
battery type when purchasing a camera.
When selecting a digital camera, I have seen many people focus entirely on resolution, extra features, capacity etc. All of these are worthwhile of course, but battery type/duration should also be a major consideration. After all, it doesn't matter how many features your digital camera has, if it runs out of power, it is completely useless.
For instance, the Sony CyberShot F505V digital camera uses a Lithium-Ion (Li-ion) battery. Unlike standard batteries, they are rechargable; and unlike other rechargable batteries, Lithium-Ion batteries don't develop any memory. This means that they can safely be recharged when only half drained without any danger of them losing their capacity.
On top of that, they charge quickly. I have two batteries for my camera. They have an operation time of 80 minutes and can be fully charged within 60 minutes.
So when selecting your next digital camera, take care to note what type of battery you are getting. Sure, those AA powered camera may be cheaper, but they won't be in the long run when you have to replace them every 20 minutes!