In reply to Andy Hudson: i have a slingshot 200AW, would recommend it to anyone
regulalry holds (but its tight) large SLR with lens attached (dont normally keep a 70-300 on it but you can with a bit of careful configuration), 10-20, 50mm, large flash gun, 17-70mm, blower and other bits and pieces. you can fit a waterproof in the top pocket if needed, but not much more. i've left out on of the larger lenses before
it is also AMAZINGLY waterproof, the other day at the beach my camera bag got totally submerged by a freak wave just after i put it down and after diving in to get it (seriously) and running screaming up the beach i found that everything inside was bone dry, and only the seams in the corner had started to show some water getting through. was amazed
accessing your kit on the move is also very easy, it doesnt look much like a camera bag, which is a big plus