hReview is a simple, open, distributed format, suitable for embedding reviews (of products, services, businesses, events, etc.) in (X)HTML, Atom, RSS, and arbitrary XML. hReview is one of several microformats open standards.
Exefen is tool for easily adding XFN values to hand-rolled links. If you're using a system like WordPress to manage your links, adding rel values is a matter of a few clicks, and this tool brings that ease of use to any page on the world wide web. It parses a given page, returns all the external links, and lets you choose XFN values for each.