Hey,
I recently came on the idea of making an UML of nearly everything. (Represent everything as visual models).
The basic idea is to start a webpage, where every user can edit this UML. Of course there have to be some version controlling, validation etc.
The general idea is that every person can add new classes to this UML and hopefully the UML once gets very well designed and big. I believe this could be very useful for a lot of people. Imagine every real world (or even virtual) objects represented in an UML.
I don't think that I will start such a webpage for now. I hope some people get inspired by this idea and make it real.

What do you think of it?