Kelty Whitney

By far the best daypack I've ever had. I got it on clearance at the local Dicks for 25 bucks, and it was definitely a great deal.

It has:
a "wire loop" internal frame
comes with a hydration bladder (a very good one too)
internal divider (laptop size)
small internal pocket with a keyring clip
waterproof pocket in lid flap
comes with a rain fly that stashes in a pocket on bottom
stash away waist belt

and there's more but that I can't think of now.

It is a very comfortable pack that breathes great, and is very durable. I've hiked with it, mountain biked, used it for a bookbag in college, and I highly recommend it if you ever were to see one (I think it's been discontinued).