AnnoCryst for PyMOL extends the functionality of PyMOL to support collaborative annotation of 3D crystallographic models. It is implemented as a plugin to PyMOL that provides an interface to browse and create annotations on structures loaded from Protein Data Bank (PDB) files. The annotations are retrieved from and stored on an annotation server using the W3C's Annotea protocol.
Website: AnnoyCryst online.
Example Pymol Script