A new section, called something like Plugin help and mentoring is created here on XF.com, where people can get help building a plugin but they have to release the plugin here as a free product.
So it works kinda like this:
You post a thread saying what you would like to build, what you have done so far, how much PHP or XF you know etc. Anyone who thinks they can help (by answering questions - not building it for you), lets you know in the thread. You get the plugin built and release it here for everyone else
People learn to make plugins, others help people make plugins, and everyone else gets the plugin
Good idea? Or one of my crap ones?