L.L.Bean Classic Continental Rucksack
Price Paid: $30
For what it is, it's amazing! is it the highest quality? maybe not. but it's a day to day smallish pack that gets it done.
It has done really well on the day to day subway commute, and even performed well during an overnight camping trip that turned out to be quite rainy and hovered around freezing. My $500 SLR stayed dry for the entire hike in and out that weekend!
Top loading and has a canvas bottom which is nice. There is 1 small pocket (keys, etc) on the inside of the main compartment. Then there are 3 others (2 side 'water bottle' pockets that each snugly fit a standard Nalgene and a front pocket that is good sized, enough for a paperback book plus other stuff).
Like the other reviewer said, for under $50 (more like $35!), this is an amazing product. Couple that with LL Bean's lifetime warranty and it's a no-brainer.