node-finder. It finds nodes.
You must replace WORLDPATH at the top of node-finder.py with the correct path to your level. Haven't gotten around to implementing command-line options yet.
Pymclevel requires YAML and Numpy installed, so this does too. Consult the project pages of each for installation instructions.
Written in Python 2.7 but as far as I know it should work on anything close. I don't believe pymclevel relies on any funky behaviour.