Particle filters in greater than 10 lines of Python code.
Amundsen will eventually be a nifty little package for simulating and using particle filters for robot localization. It will include various kinds of sensors (that can either generate simulated data or use data from real sensors), a software-defined "robot", facilities to input and use various types of maps, and some nifty visualizations.
Right now Amundsen is a mostly-empty Github repository. One of so, so many.
MIT License. See LICENSE.txt.