User Review: Mountainsmith Day
Design: Lumbar Pack
Number of Pockets: 3
Max. Load Carried: 13lbs
Height of Owner: 5'11 (torso: 19")
Price Paid: ~$70
Moutainsmith makes a big line of "lumbar packs" that fit in the small of your back. They are good for carrying lighter loads for active sports because they hug your back and keep the weight close to your center of gravity. The belt goes higher than a regular pack belt, around your waist. This can be inconvinient, especially when hiking with a full bladder ('nuff said).
I have found it to be OK for light loads, but they market it as a daypack and it really can't handle the weight of water, jacket, etc for a day hike. They make a padded belt you can add (for another 20 bucks or so) to make heavier loads a little more comfortable.
I have found that it doubles well for carrying books (the belt hides away and it has a shoulder strap) and especially convinient for carrying a laptop computer through an airport (leaves your hands free for luggage), but for dayhikes I have to stick with a standard daypack (I love my Jandd).