  The interface between domains of opposite magnetization in the 3D Ising model
near the critical temperature displays universal finite-size effects which can
be described in terms of a gaussian model of capillary waves. It turns out that
these finite-size corrections depend rather strongly on the shape of the
lattice. This prediction, which has no adjustable parameters, is tested and
accurately verified for various lattice shapes by means of numerical
simulations with a cluster algorithm. This supports also a long-standing
conjecture on the finite-size effects in Wilson loops of Lattice Gauge
Theories.
