  We calculate frequencies and damping rates of the lowest collective modes of
a dilute Bose gas confined in an anisotropic trapping potential above the
Bose-Einstein transition temperature. From the Boltzmann equation with a
simplified collision integral we derive a general dispersion relation that
interpolates between the collisionless and hydrodynamic regimes. In the case of
axially symmetric traps we obtain explicit expressions for the frequencies and
damping rates of the lowest modes in terms of a phenomenological collision
time. Our results are compared with microscopic calculations and experiments.
