SnapPy is a user interface to the SnapPea kernel which runs on Mac OS X, Linux, and Windows. SnapPy combines a link editor and 3D-graphics for Dirichlet domains and cusp neighborhoods with a powerful command-line interface based on the Python programming language. You can see it in action, learn how to install it, and read the tutorial.
Written by Marc Culler and Nathan Dunfield. Uses the SnapPea kernel written by Jeff Weeks. Released under the terms of the GNU General Public License.