Theory of Computation of Multidimensional Entropy with an Application to   the Monomer-Dimer Problem
  We outline the most recent theory for the computation of the exponential growth rate of the number of configurations on a multi-dimensional grid. As an application we compute the monomer-dimer constant for the 2-dimensional grid to 8 decimal digits, agreeing with the heuristic computations of Baxter, and for the 3-dimensional grid with an error smaller than 1.35%. 
Shmuel Friedland, Uri N. Peled