This isn't super flashy, but this game (http://dominion.isotropic.org/gamelog/201109/16/game-20110916-155730-c4d1b50f.html) features some of my all-time favorite Contraband prohibitions.
We were both buying Contraband because it was the only $5 card on the board and we wanted to Remake them into Golds and Nobles. At first, sure, it's pretty mundane: I made sure he couldn't get his first Gold off a Contraband buy. Which isn't completely the end of the world for him, since he can buy Nobles instead.
Then the endgame rolled around, and he was behind, so he had to rely on Contraband for cash and buys attempting to catch up. Again, at first, it's mundane: It's greening time, so I prohibit Provinces, and he buys lesser VP cards instead:
— Leonard's turn 14 —
Leonard plays a Contraband.
... led prohibits Leonard from buying Provinces.
Leonard plays 4 Coppers and 2 Silvers.
Leonard buys a Duchy.
Leonard buys a Duchy.
— Leonard's turn 15 —
Leonard plays a Contraband.
... led prohibits Leonard from buying Provinces.
Leonard plays 3 Silvers.
Leonard buys a Duchy.
Leonard buys an Estate.
Leonard buys an Estate.
But then we get down to 1 Province left in the pile, and I realize hey! If he buys it I've got enough VPs to hold him off. The only way I can lose is if he gets too many Duchies first and then buys it. So here's where I make a really fun play I've never gotten to try before:
— Leonard's turn 16 —
Leonard plays a Contraband.
... led prohibits Leonard from buying Duchies.
Leonard plays 2 Coppers.
Leonard buys an Estate.
Leonard buys an Estate.
Leonard buys an Estate.
Leonard buys an Estate.
— Leonard's turn 17 —
Leonard plays a Contraband.
... led prohibits Leonard from buying Duchies.
Leonard plays a Copper and a Silver.
Leonard buys an Estate.
Leonard buys an Estate.