Kenda Super Lite 60mm valve (85g) on one bike
Cutter Premium 60mm valve (got these from Bonktown/CL) on the other bike
Have also used tubes from my LBS and also the ones from Performance
The Kenda are my favorite tube because they are light, decent price ($5), and have good valve stems (nickel plated? and high quality heads than haven't ripped off or shred the pump)
I need to find some decently priced 80mm tubes though because valve extenders suck...