have a Balin triple, usually use as a double though. Been all around and no serious board damage though its getting pretty ragged now. Those SOMA airbags look trick though "http://airbagdesigns.com/soma.htm"
I got a XM single longboard bag from Kona in Wildwood . It cost me 50 dollars and it really nice . Its got a big pocket in the side to store your leash or a wetsuit and it has pockets inside the it to store your fins aswell. For going local I use a board sock its alot easier to to load and unload on the roof of my car
On the costa rica trip i went on, i used a single day light dakine surfboard bag for 40 bucks... I fit two boards in pretty easy, and put a sheet of cardboard on the top and bottom, it worked awesome, not a single dent or anything on the PU board or the epoxy! and even better, it only cost me 60 bucks to bring it!