Fluidinfo
Wikipedia for metadata. With a business model.
Fluidinfo is a universal metadata engine with an object for everything. Regular users, applications and content owners can write, search on, and share metadata about anything. Fludinfo released a UI in Jan 2012, launching 'next generation tagging'. Tag values can be URLs allowing tagging with images, sounds and video, displayed as rich content. Users are able to curate and share their own content on any object. Fluidinfo is aimed at consumers and at enterprise Knowledge Management.