Okay, this is fairly ingenious. Here’s a wiki spin-off which places small purple permalinks at the bottom of each paragraph, so that you can refer to them elsewhere. I was wondering how they deal with matching the right permalinks to paragraphs that have changed (do some sort of ingenious diff? Some weird Xanadu-derived algorithm?). Then I played around, and I realised – they just use the Wiki nature. The program sticks in a permalink whenever it sees a paragraph without one. It appears in the text itself as “{nid0}”. Wiki editors choose where it should go.
Currently:
purplewiki