How about implementing the facility to a leave feedback score about opponents when the game or match is finished, and the feedback left could be displayed on their profile.for example a rating out of 5 on your gaming experience with that player.This will then give people information about the particular player they are playing with.

Edited at 01:21 Wed 30/05/07 (BST)

sounds good but there will be something waiting to go wrong

Sounds like a good idea...But you could get sore losers leaving a 0 or 1 every time they get beaten, or just people that don't like others would leave bad feedback etc.

yep knew that there would be a catch there always is