Sega is slapping discounts on several of its iOS offerings through November 29. Lots of Genesis games have been knocked to $0.99, including Sonic 1 and 2, Sonic Spinball, Streets of Rage 1 and 2, Virtua Fighter 2, Altered Beast and Gunstar Heroes. Super Monkey Ball 1 and 2 are also down to $0.99, while Sonic the Hedgehog 4 - Episode 1 can be had for $2.99 (the Windows Phone version has been reduced to $4.99).
Granted, many of the titles aren't terribly playable with virtual controls, but they aren't without their purpose. For example, Gunstar Heroes is perfect for convincing your grabby little cousins that your iPhone isn't worth playing.