I think that some of these would be great to use! However, I don't know how we would come about these w/o either a) using the oils or b) putting them into the liquid. I guess we could try soaking them like some have done with cigs...
Herbs for Vaporizers (has a list of common added herbs in cigs to give them a 'hit')= www dot silversurfervap dot com/herbs dot htm
Herbal Blends for Vaporizers (more medicinal then recrational) = www dot gotvape dot com/medicinal_herbs/herbal.blends.for.vaporizers dot php
Herbs to Avoid (self explanitory) = www dot gotvape dot com/medicinal_herbs/herbs.to.avoid dot php
There you have it! Sorry for the messy url's but I don't have enough posts racked up yet. Now I haven't scoured over these, but they are out there if anyone wants to play with them.