Hi Just bought a Lowepro slingshoot 200 for my 400D with 2 lens.
Not sure if that is what you are looking for. LIke the backpack sling bag so that it keep 2 free hands. easy to slide it in front to get equip without removing the bag from shoulders. kind of neat for on the go shoot.
Solar panel backpack with battery pack to recharge your camera batteries and any other electronic gadgets. You can even buy the solar panels or the battery system to create your own ultimate backpack.
This would be great if you are planning to trek to some obscure location without electrical source.
Other than that, who needs a camera bag, I use my handbag or the classic red plastic shopping bag