Collaborative development of teaching materials and assessments
It's a wonderful idea.

In the spirit of start somewhere, how about:


Publish these teaching materials (pictures, notes and so on that you have developed to explain a particular concept) on a website of your own, and open it up to moderated comments.  Invite others to contribute guest posts.  You might want to include something like this: "You are free to use these materials in your own teaching, as long as you acknowledge the source."
Borrow liberally from this and create one or more Wikipedia articles.
Consider asking your university to videotape your lectures.
Write up a more scholarly version for publication in a journal.