  We discuss the problem to count, or, more modestly, to estimate the number
f(m,n) of unimodular triangulations of the planar grid of size $m\times n$.
  Among other tools, we employ recursions that allow one to compute the (huge)
number of triangulations for small m and rather large n by dynamic programming;
we show that this computation can be done in polynomial time if m is fixed, and
present computational results from our implementation of this approach.
  We also present new upper and lower bounds for large m and n, and we report
about results obtained from a computer simulation of the random walk that is
generated by flips.
