Using python to extend a python app

[dataangel]

I'm writing a python app that works as a replacement for the menu that 
comes with most minimalist wms when you right click the root window. 
It's prettier and written completely in python.

I'd like to provide hooks or some system so that people can write their 
own extensions to the app, for example adding fluxbox options, and then 
fluxbox users can choose to use that extension. But I'm not sure how to 
implement it.

Right now the best idea I have is to have all desired extensions in a 
folder, import each .py file in that folder as a module using 
__import__, and then call some predetermined method, say "start", and 
pass it the menu as it exists so far so they can add to it, start(menu). 
This seems kind of hackish.

I looked at how gdesklets handles this, but its solution looks way more 
complex than I'd prefer to have to dive into for this tiny app.

What's the most pythonic way to do this? How do apps that extend 
themselves with python usually do this?