Partio is an open source C++ library for reading, writing, and manipulating
a variety of standard particle formats (GEO, BGEO, PTC, PDB, PDA).  It acts
as an abstraction for the commonalities in particle models (i.e., accessing
many attributes associated with an index or entity).

Partio has a Python API and a collection of simple command-line tools.

WWW: http://partio.us/