TeleScooby
Adventurer
Lowepro is the way to go for a photo specific backpack, I also have the PhotoTrekker AW, for when I need to have the bulk of my gear with me. Otherwise I use a combination product from Crumpler. It's my everyday shoulder bag with a padded, divided insert in it. I loved this set up in NY last month, because you couldn't tell what I had in the bag, it looked just like every other messenger bad on the street, but it housed my D70, two lenses, and a compact video camera...