I'd recommend a Timbuk2 bag if you can afford it and aren't worried about wanting something "stylish". (I don't really know the word for that. I just mean that I wouldn't bring mine to a business meeting or really nice restaurant) Anyway, they come in all kinds of shapes and sizes and colors. Since you're carrying a camera, I'd probably get one of the laptop bags since they are padded on the inside...I carry my camera around in mine and it's a fairly substantial camera. There's all kinds of pockets, zippers, and such and most of the bigger ones come with a cross strap (if you go for the messenger type) that you can fasten to keep it from swinging while you ride or walk. They also make an "outawhack backpack" that is essentially a messenger bag that can also be carried like a backpack. Anyway, hope this helps. If you aren't into the Tiimbuk2 thing, then I'd suggest checking out LLBean...they have some awesome packs and stuff. My big backpack is from there and it's awesome.
Take care and have fun,
Gray