This is coming up ... but before development can start, there are a few things that need to be figured out.
1) I want to get away from the "white belt, green belt, black belt" thing. People start wanting to talk about too many other things.
2) After a lot of thought, I rather like the idea of four levels: sand, reed, wood and iron. So the colors would be off white, green, brown and dark gray.
3) I liked the belt system before because somebody could say "I have a black belt in natural building" or "I have a black belt in gardening". So, maybe that can be replaced with "I have an iron belt in gardening". ??
4) Once a level is achieved, then it can be displayed in the signature line. So the question becomes: how is it displayed? There might be 24 different things. Maybe even more eventually. But let's say there are 24. Maybe each one is an icon that is 32 pixels wide and 50 pixels high?