HalfPy is a stripped-down version of the Python 2.3 source code with no support for an interactive prompt, a parser or a compiler. It is essentially just the byte-code interpreter / Python VM part of Python.
Part of the Cleese project.
After a solid 12-hour coding session, I've managed to successfully put together a first pass of what I'm calling "HalfPy".
I put it together by building up a new source tree one file at a time, copying over files from the standard source tree and modifying them as necessary in order to get it to compile without having to include parser or compiler code.
It was relatively straight forward (even for an inexperienced C programmer like myself), although there were a couple of places where compiler code was mixed in with byte-code interpreter code (most notably in compiler.c) which made it a little more involved.
HalfPy compiles on Cygwin - I doubt it will currently work on anything else as I took a lot of liberties with regard to #defines and I hardcoded files that in the original source are generated via autoconf.
There are still some warts and potentially a fair bit of work to do, but what you end up with when you type 'make' meets the initial objective: you can run a pre-compiled helloworld.pyc
I've checked the code into our SourceForge CVS.