System already in place at TheOne's Build server. Basically it allows one to keep track of every block placed or destroyed by a person. An admin can later say a command (IE /whodid) place a block (in the event of a destroyed brick) or destroy a brick (For brick placement spam) and see a list of the last five or so who edited it, and say another command (IE /undoactions fred) and everything they have done will be reversed. This is without a doubt the best anti-greif tool I have ever used, as it doesn't bother anything (No registering or anything) and greif can be easily undone.