Deal Out the Deck
(Originally posted on BoardGameGeek.)
A strategic (long-term planning / thinking) variant:
Instead of two cards drawn each turn, deal out the deck (3/4/4/5/7 card hands for 8/7/6/5/4 players), leaving the odd remaining cards face-down in the middle as spares.
On your turn, choose a card from your hand, set the help arrows (one must go on your card, the other on any other card), and offer the card as usual.
This means you have more options for bluffing your card and/or signaling to your teammates. You also have (in the lower player counts) more of a chance to gather information early. It is a ton more information, so the game will get heavier.