Links: Card Game Discussion Groups and Mailing Lists
BoardGameGeek has a guild called Playing Card Games Enthusiasts, which is a forum for discussing card games.
The newsgroup rec.games.playing-cards is for discussion of all games played with playing-cards. If you don't have a newsreader, you can also access the rec.games.playing-cards group using a web browser via Google.
Certain card and tile games have their own more specialised newsgroups and forums, for example: