We show that a normal (single particle) current density Jx {\em
transverse} to the ordering wavevector 2kFz^ of a charge density
wave (CDW) has dramatic effects both above and {\em below} the CDW depinning
transition. It exponentially (in Jx) enhances CDW correlations, and
exponentially suppresses the longitudinal depinning field. The intermediate
longitudinal I-V relation also changes, acquiring a {\em linear} regime. We
propose a novel ``current effect transistor'' whose CDW channel is turned on by
a transverse current. Our results also have important implications for the
recently proposed ``striped phase'' of the high-Tc superconductors.Comment: change of title and minor corrections, 4 RevTeX pgs, to appear in
Phys. Rev. Lett., 81, 3711 (1998