Diego Inácio has created several geometry tools for Houdini, using Python.
Houdini 13 Update
Side Effects's latest version of Houdini 13 comes with new particles, finite element solver, lighting workflow and more.
SideFX have announced Houdini Engine, an API that will facilitate Houdini integration into proprietary studio software.
See the new features and improvements in Side Effects Software's fresh release of Houdini 12.5.