Google is built on the
PageRank system which uses the interrelatedness of web sites to determine the relative importance of the sites' content. I was thinking about the GMail systyem, almost everyone now has a GMail account so this system doesn't make a great deal of sense - unless you realise a side benefit of such a system. The GMail invite system provides a degree of interrelatedness between Email accounts - I wonder what use this information is being assigned? If you're able to track emails as they pass between email accounts (as I guess GMail could easily do), it'd provide and awesome way to track trends and emergent fashions and a REALLY powerful marketing tool!