Could a e-cig give you cancer even if the liquid doesn't have nicotine in it?

Nobody knows: There are zero studies of e-cigs, and nobody knows what they will do, even with no nicotine. Nicotine is not the cause of cancer anyway - it is the complex hydrocarbons (tars) in the smoke. It is likely that e-cigs will prove safer than smoked cigarettes, but again, nobody really knows. The propellant in these gadgets is propylene glycol, and nobody knows what inhaling them, or the oils, will do.