Marcus Martin's list of force field references (http://towhee.sourceforge.net/references.html)

FSAtom (http://www.fsatom.org/) and its wiki (http://dirac.cnrs-orleans.fr/fsatom_wiki/)

CML (http://cml.sourceforge.net/)

A. Pedretti, L. Villa, G. Vistoli, ATOM-TYPE DESCRIPTION LANGUAGE: A UNIVERSAL LANGUAGE TO RECOGNIZE ATOM TYPES IMPLEMENTED IN THE VEGA PROGRAM (http://www.ddl.unimi.it/papers/07/Teo.Chem.Acc.109_2003.pdf), Theor. Chem. Acc., Vol. 109 (4), 229-32 (2003).

Junmei Wang, Wei Wang, Peter A. Kollman and David A. Case, "Automatic atom type and bond type perception in molecular mechanical calculations (http://dx.doi.org/10.1016/j.jmgm.2005.12.005)," Journal of Molecular Graphics and Modelling, Article in Press, Corrected Proof. (describes the Antechamber package)

Antechamber