Tank is a service for creating, keeping, managing and sharing content online in an environment that encourages linking between things to build hypertextual webs of information.
Tank could be described as an enhanced wiki. It has the features expected in a wiki (quick linking, easy formatting, recent changes) that enable excellent personal notebooks and small group collaboration and it has features that allow multiple types of content, diverse modes of sharing and easy use and creation of custom applications that work the content.