  Mean-field calculations for the two dimensional electron gas (2DEG) in a
large magnetic field with a partially filled Landau level with index $N\geq 2$
consistently yield ``stripe-ordered'' charge-density wave ground-states, for
much the same reason that frustrated phase separation leads to stripe ordered
states in doped Mott insulators. We have studied the effects of quantum and
thermal fluctuations about such a state and show that they can lead to a set of
electronic liquid crystalline states, particularly a stripe-nematic phase which
is stable at $T>0$. Recent measurements of the longitudinal resistivity of a
set of quantum Hall devices have revealed that these systems spontaneously
develop, at low temepratures, a very large anisotropy. We interpret these
experiments as evidence for a stripe nematic phase, and propose a general phase
diagram for this system.
