Fencer,

Alot of the discussion around here is how to correct ratings for cheaters, but what if you just identify who those cheaters are? That is, since the ratings in all the games (even the win/loss ratios) can be "cheated", why dont you identify the users who are "cheaters" but a value (boolean?). This value would display their name in green or something so that others could see they were known cheaters. This value could also be used to remove them from ratings lists or tournaments.

If you want to be fair, you could also have this value reset after X time or stay permanent (if the account was banned maybe).

friendjosh