I think it would be cool to gamble cards, but allow it to be an option. People would start being picky about what kind of cards they play. Also, a setting limited rules for your own games like, "Highest number 7" or something would be kind of nice so people can play lower card decks and not absolutely destroy them if that was a rule set they decided on. I personally set up a "newbie" set so I can play and teach other players how to play while leveling the playing field.
Edit: Then again, players could abuse this, it would be fun imo.
