Osprey Helios 8

I know that lumbar packs don't get a great deal of respect, but they can be ideal daypacks in warmer months. I've found that to be especially true for the Osprey Helios 8. The design is fantastic and the build quality is extremely high like you'd expect from Osprey. I first bought a Mountainsmith Blaze lumbar pack but it wouldn't compress very well and so didn't keep the weight centered and close to the lower back. I was always aware that I was carrying this thing on my hips (a nice pack for casual use though, designed for office/travel/school use with lots of organizer pockets, pen slots, etc).

The Osprey is more all-business and is extremely comfortable. It's a little taller and thinner to keep the weight centered with the wearer's center of gravity. It also tapers internally rather than having a box-like bottom which enhances performance. The online pics don't show the side mesh pockets in use which is a shame because they are perfectly designed for water bottles (the bottles aren't way out on the sides like some packs). And the back shovel pocket/compression panel does a spectacular job of compressing the contents tightly even when lightly loaded, so it rides flawlessly.

Minor extras I didn't expect: An outer map pocket with key clip and an inner elastic divider you can use to separate your food from gear, wet from dry, etc.

Very highly recommended over lumbar packs from North Face, Mountainsmith, Arc'Teryx and the others. Try it - you'll be glad you did!