Beyond η/s=1/4π

We use a low-energy e. ective description of gauge theory/string theory duality to argue that the Kovtun-Son-Starinets viscosity bound is generically violated in super conformal gauge theories with non-equal central charges c not equal a. We present new examples (of string theory constructions and of gauge theories) where the bound is violated in a controllable setting. We consider the comparison of results from AdS/CFT calculations to the QCD plasma in the context of this discussion.