But has anyone thought about marketing in a way that brings BACK old players? I've always though the best way for people to get into CF was through word of mouth, and that's most likely to happen from people who've had good experiences with CF in the past.

I think it would be a neat idea if you were to gather up all the emails attached to accounts from this forum and send them a Carrion Fields newsletter describing all the new cool features on the MUD. Attach a survey to see what it would take to get them to come back to the MUD after all these days/months/years. I know sending out emails in this fashion is somewhat taboo, but I think it's worth a shot.

Basically just remind them why they like crack and why they should start smoking it again.