I've leisurely started to do wiki pages[1] on oUF over at GitHub, so those who want can give a helping hand. You generally shouldn't have to worry too much about quality for now
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There's still some changes missing in the 1.4 branch when it comes to the element system, so I'd advice people not to tackle a "General element usage" page just yet. Also the "API Documentation and Reference" list on the Home page can be discarded. I tried to map it all out yesterday, but I'm quite far from satisfied with the list. Feel free to take a stab at improving it tho'. :3
[1]
http://wiki.github.com/haste/oUF/