A coworker and I are looking for camera backpacks. Where are some good places to look, and most importantly, what are some good brands. Preferrably something with a waterproof cover. I'll need something big. Something to hold my list of equipment that's in my signature...including room to expand 2 or 3 more lenses possibly. She will need something to hold an XT, a 18-55, a 28-135 IS, and a smaller 80-200 Canon. I suppose a better question would be: If you have used a camera backpack, which model was it, what did you like about it, and where can I find it?