PyKDE, written and actively maintained by Jim Bublitz, is a full interface to KDE's libraries. This allows you to write fully-fledged KDE applications with python.
Documentation is available at Riverbank Computing Limited.
If you have written an application for PyKDE, please list it here:
Frescobaldi is a LilyPond music text editor written in Python using PyKDE4
pyRad is a wheel type command interface to allow quick access to programs.