From Rosetta Code
Psyco is an implementation of Python. Other implementations of Python.

From Wikipedia:

Psyco is a specializing just-in-time compiler for Python.
Psyco is written in C and generates only x86-based code.

On March 12, 2012, Psyco was announced to be "unmaintained and dead".
A follow-up project to Psyco is PyPy.