first definiton of nemesis: players you don´t want to meet on a server because they ruin the game for you. To good (like some of the 25K:0D players that are on lately) to have a nice game with or because they know no teamplay at all. Blacklist for this people would be great too
One suggestion:
Make a color highlight in the server browser:
- green for server with friends
- red for servers with nemesis
If you could use the filter to sort out servers with nemesis players this would be helpfull too.