http://www.kata-bags.com/product.asp...&Version=Photo
I bought this before my trip to Australia. I wanted a bag that would carry my D300+battery grip and my 2 lenses, 85mm F/1.4 and my 17-55 f/2.8.
I love the way it can be either a back pack or a sling bag. I used it a lot in the sling bag configuration when i was in an area where i was taking lots of photos but didnt want to carry the camera in my hand. The side access pockets were perfect for this.
I would then put it back in the backpack config when i was just on the bus or walking to a location i wanted to shoot at.
It came with a little rain cover, and some extra dividers.
Not only did it fit my camera and 2 lenses, but it also fit my SB800 and 2 pocket wizards, a lens hood for the 85mm and a sandwich bag full of AA batteries. And the external hoop allowed me to attach my tripod. I just hung it with an extra strap i had laying around from my camping gear.
As well there was some extra space in the top compartment for either an extra medium sized lens or a sandwich, chips and wallet/papers, iphone/ipod, PnS camera or what ever other accessory you might want to put up there.
My only complaints are not really against the bag, but the lack of such a similar bag design that would accommodate a 15" laptop + a few accessories like external HDD, AC cord, battery.
I chose the middle of the range, (the 20) vs the 10 or 30. The others felt too small or too big for a day pack for all my gear that i wanted to lug around.