Group items tagged

Digress.it is a plugin for WordPress that supports discussion at a far finer level than is traditionally available on most blogs. Rather than limiting conversations to a single field at the bottom of a post, digress.it "lets you comment paragraph by paragraph in the margins of a text." -- Mike Bogle, TechTicker

I'm continually looking for a way to use this but so far haven't found one. For personal blogs with fairly short posts it's a bit of overkill I think, but I could easily see it used for longer pieces - especially where you're meticulously analysing or interpreting things.