> You give the Ouya a look? I'm not sure if you can run the MAME4Droid on it or not.
Ouya has the same internals as the Google Nexus 7 tablet, which runs MAME4Droid Reloaded (MAME 0.139, so not totally latest but it should cover what the OP's after) reasonably well for 8 and 16 bit games (Space Harrier even manages 60/60 with sound, but other Sega multi-CPU games get stuttery).
That said, Tegra 3's getting pretty long in the tooth and there will be better Android solutions than the Ouya soon (Nvidia's just-announced Android gaming handheld should be ideal for modern MAME CPU-wise with 4 Cortex-A15 cores, but pricing remains to be seen).
ETA: I should note that ARM solutions currently don't have a backend for MAME's recompiler, so certain classes of games that run well now on low-end x86 won't work as well on those systems: Killer Instinct, CPS3, and Kaneko Super Nova being the 3 notables.