From Tony Hill and a DP forum thread, comes the amazing news that Adsense is now showing publishers how much money they've taken back because of invalid clicks! If you go to My Account / Payment History and click on one of the Earnings links, you'll see a summary of the earnings, which now supposedly include how much Google has taken back due to invalid clicks. Now, I can't confirm this because mine doesn't show any invalid clicks, but I don't know if that's because I haven't had any, or this rumor is untrue. If, however, it is true, then I think this is a GREAT move on the part of Google. Let me know if you see it in your account.