For 3-7 players.  Uses a standard 52-card deck.

1. Shuffle, deal 7 cards to each player.
2. Players trade cards amongst themselves.
3. After a while (time limit?) trading ends.
4. Each player uses the cards they have to construct the highest-scoring poker hand they can.
5. Highest hand wins.

The information problem

Notice I’ve said nothing about what sort of information is allowed to be passed.  How do you know the other person will stick to their deal?  Do you have to reveal the cards before trading them?  What happens if you trade cards and suddenly someone says “Wait, you said it was a heart, but this is only a 3 of hearts!  I don’t want this, give me back my card!”.  Also, is it difficult to make deals with someone sitting across the table from you?

Playing on a computer solves many of these problems.  Any decent chatroom interface allows the players to chat with each other both publically and privately.  Also, I can envision a trading interface that would make things easy.  The trading interface would look something like this:

1. You choose a card(s) to offer.
2. You choose how to present those card(s).  If you were trading the 7 of hearts, there would be options for calling it “One 7″, “One H”, “One Red”, “7H”.
3. When both players are finished with the trade, they see the details of the trade and can examine it.  (“Trading One 7 For One D”)
4. If both players confirm, the trade is executed.  If either player cancels, the trade is cancelled.

This solves the problem of not getting what you expected by making it part of the game.  Yes, you might have gotten a 2H, but you saw that you were getting “One H” and you pressed “Confirm”–it’s your fault!

Notes

You may trade unequal numbers of cards.  Is a hand with four cards a legal hand?  I would say for this game it should be.  If you trade away all but four cards, but those four cards are four kings, you deserve to win!

Obviously there’s room for variation; giving the players fewer cards to start with would probably restrict their freedom, but giving them too many would shift the emphasis more toward simply arranging the cards you already had.  Playtesting is certainly a good idea here.  One thing that might be fun would be to shuffle two decks together; that way things become more uncertain and random.