  Numerical simulations have shown that the recently proposed "crab waist"
scheme of beam-beam collisions can substantially boost the luminosity of
existing and future electron-positron colliders. In this paper we describe the
crab waist concept and discuss potential advantages that such a scheme can
provide. We also present the results of beam-beam simulations for the two
currently proposed projects based on the crab waist scheme: the DAFNE upgrade
and the Super B-factory project.
