jpch - 8:17 pm on May 22, 2013 (gmt 0)
In Chrome it allows you to see information about the ads appearing on your sites and to send feedback to G about those ads. Of course it also allows you to see your earnings. I would think it would be useful for someone that's aggressively filtering ads for their sites but don't know for sure. There might be other uses those just seem like the obvious ones.