I've always liked what Mercurial's docs were trying to do (http://hgbook.red-bean.com/read/customizing-the-output-of-me...) by having comments at every paragraph of their docs. It's done about 10% as well as it could be though. You almost want stackoverflow style questions to link to direct paragraphs or maybe even sentences.

Maybe overlaying something like rap genius' tools on existing docs is enough?

Looks really nice so far, but I don't use ruby so can't vouch for accuracy of search etc...