I always liked the idea in old school trading card games you could wager your rarest card on the outcome of the match.
Then again, serious gambling issues run in my family...
But, what if there were a new class of "super" rare cards released that if you lost a match and your opponent wins it on a spin, you lose it?
Then a new system to notify you of such events would have be implemented, but you get the idea?
I don't know how much traction such an idea would get... but I think it's interesting.