Digg has finally released its recommendation engine. As users have incresed digg-ing news item to digg the vast number has made it difficult to know what to look at. The Digg engine matches your digg entries with other digg users to try and suggest or recommend content that is being digged by those users.
Digg Recommendation Engine from Kevin Rose on Vimeo.
Lotus Connections has a similar notion. When I look at My bookmarks within Lotus Connections Dogear (tagging) component the system correlates the tags I am interested in with other IBM employees irrespective of their location or business unit. This allows me to make contact with colleagues who have similar interests to me which is useful when you are trying to develop your knowledge network. This group of people may share other interests with you as well so a really cool feature.