Sitting beside me in the airport is my Granite Gear Virga ($110), the frameless pack I’ve been using for the last number of years. I’ve no plans to switch anytime soon.
The “frame” is a standard 3/4 short therm-a-rest mattress.
Manufacturers of Frameless Backpacks include:
Gossamer Gear
Six Moons Design
Golite
ULA Equipment
Granite Gear
Osprey
Fanatic Fringe
Mountain Laurel Designs
Moonbow GearSource to Sea – Advantages of Frameless Backpacks
Will Rietveld is the expert.
He’s been updating his Frameless Backpack Review Summary for BackpackingLight.com since 2004.
The article is only available for Premium members ($25/yr) however – Lightweight Frameless Backpacks State of the Market Report 2011: Part 1 – Choosing and Using a Frameless Pack
Don’t knock them until you’ve tried one. For me personally, the “suspension” system packs still have pressure points. Frameless are much more comfortable.
related post – tutorial – how to pack a backpack (VIDEO & PHOTOS)
besthike.com 
I recently “discovered” frameless packs. I’d been hauling a 6lb+ 90L Kelty around for far too long. Since most of my other gear is lightweight anyway, I bought a SMD Starlite and use a Z-Rest for the frame along with an aluminum stay. I’ve only packed it up and walked around my apartment, but it feels good even at 35lbs. Just in changing to a frameless pack, I’ve managed to knock-off 4.5lbs – which is nothing short of amazing.
That may have been my finest gift to you ever Rick 🙂 Never imagined that you would still have one this many years later, albeit not the original. And I still absolutely love the Latitude that you recommended, in my opinion the most brilliant backpack I have ever owned. Love those types of exchanges..
THANKS once again, George.
Someday I’ll switch. But I can’t imagine why. This one is perfect, aside from the colour.