I have a reasonably big bag, it has an across the chest strap so the weight tends to be distributed a bit better for carrying.
I use a bigger one as i cart my G11 camera, iphone, and Kindle 3 if i'm going anywhere that i may have to wait.
I also carry a wallet equipped with the usual cards etc, my heart med, and my migraine meds, so as you can see a little one would not be so suitable for me .Mine is the traditional shape, no cat shape here, the dogs would get jealous ...