This is something I am interested in too. I use to air dry my hair, but itís way too cold to go out with wet hair up here in the Last Frontier now. (We had 2 F yesterday :P ...which isn't the usual for this time of year).
I use the bowl diffuser w/fingers. Not too bad of a frizz actually, but I am afraid of damaging the hair...On the other hand I don't want to get pneumonia either.
I actually find that my hair look better if I dry it a bit too this way. It can look abit droppy sometimes just from air drying it.