Wolumes - An algorithm to compute the volume of atoms and residues in   proteins
  Wolumes is a fast and stand-alone computer program written in standard C that allows the measure of atom volumes in proteins. Its algorithm is a simple discretization of the space by means of a grid of points at 0.75 Angstroms from each other and it uses a set of van der Waals radii optimized for protein atoms. By comparing the computed values with distributions derived from a non-redundant subset of the Protein Data Bank, the new methods allows to identify atoms and residues abnormally large/small. The source code is freely available, together with some examples. 
Oliviero Carugo
q-bio.BM