ObKey is the Openbox Key Editor, written in Python + PyGTK.
The latest version is 1.0 (looks stable). Development is halted.
PyGTK 2.14 is REQUIRED
Simply unpack it (or clone git repo) and run as the python script, by default it uses ~/.config/openbox/rc.xml as a config file containing keyboard setup.
But also you can specify other config file:
Screenshot (more recent than a demo below):
Also there is a screencast, maybe a little boring (about 6-7 megs, swf):