When backpacking, I take this tiny digital camera with me for snap shots.
It's a compromise for me. I'd rather be getting excellent shots with a digital SLR but a) it's hard to justify the weight and b) I find when I'm backpacking I don't want to be faffing around with all the setup needed to get those killer shots.
I went with the Optio as is only weighs 4.2 oz. and has a lot of features. It's a 5 megapixel camera, so has decent resolution and with a 512 mb SD card, I can take about 140 shots. Even with all the opening and closing of the lens, I have never drained a fully charged battery on a single trip.
You can't buy this camera anymore – it's a old model, I think the Pentax Optio 750z has replaced it (an 8 megapixel version), but the weight has gone up.
If you're in the market for a new ultralight camera, I'm sure there are better options at this point in time. Anyone care to suggest?
Read the digital photography review on the Pentax Optio S5i.