|This code has been put under version control in the project Pymol-script-repo|
MSMS is an excellent tool for computing protein solvent excluded surface (SES). MSMS Plugin for PyMOL provides a graphical user interface for running MSMS and displaying its results in PyMOL. See the original site (not updated anymore) for more details: MSMS Plugin for PyMOL
Most recent MSMS Plugin code can be obtained from this link.