There is an interesting part of thread http://typophile.com/node/15724 people should see. (Look at the end where Mark posts his plans for his fonts and where Karsten has posted his little manual.)
I wonder if we all put our collective heads together, we could develop the primary needs for an Opentype guide/manual which type designers could post with their fonts. There are a great many Opentype bells and whistles which go unused just for lack of knowledge.
I am hoping this will end up as a document aimed at graphic designers and typographers who use type in more sophisticated ways than the typical word processor folks but not so geeky that people get lost or turned off by it.
The floor is open . . .