Very neat ideas — and I DEFINITELY see how tags in flickr would break down very quickly. I totally agree with what you say about tags — I’m also thinking of them less and less as a meaningful organizing tool. Instead, they are a discovery tool, and organizing and discovering don’t always overlap.

As for other tools to work with this kind of semantics, the one that first springs to mind is Wordnet. It’ll likely take some work to sort through the symsets and whatnot, but it likely has the semantic data to work with.

Oh…and last thing, as a former English prof, I’d definitely advocate keeping the word repetitions in place. As a first interpretive step, I always taught students to first find the repetitions — those will always be an important guide.

Good luck!
Patrick