This is what I use. Mine only has one shoulder strap though, my ex gave it to me a long time ago in singular strap form. Works very well, no back pains or anything. The weight distribution is freaking awesome. I was going to buy a larger backpack or messenger bag but screw that. I'm keeping this for my 'tool bag' and quick trip bag and getting a pannier setup for anything that wont fit in it.

Also the newer models (http://www.mountainsmith.com/product...bCategory2Id=0 check Mountain Smith's website) are *much* cooler than this. A lot more er, ergonomic, I guess you could say. They look a lot more comfy than the version I have (which I believe is about 6 years old or so). Not to say mine isn't comfortable, but when loaded down beyond what I would say is the suggested carry weight it kind of sucks, but it would in any bag really.

Edit: It's called the Mountain Smith Day or Mountain Smith Day Daypack