Along these same lines - anyone who is interested in optimizing their indexes based on live usage patterns should check out this blog entry from sqlcat on related dmv's:

http://blogs.msdn.com/sqlcat/archive/2006/02/13/531339.aspx

And you may want to play with this (unsupported) script from the sql query optimization team, it can automatically implement recommended index changes for your db:

http://blogs.msdn.com/queryoptteam/archive/2006/06/01/613516.aspx