Someone created, as stated in the title, an MS-DOS emulator with ~2400 games to play.
And one game caught my eye. Go Allegroids.
Go Allegroids.
Ahem. We prefer the term Allegators.
... not really, though maybe for this thread.
I recently installed DOSBox on my Nexus 7. Works great. 
It's DOSBox compiled with asm.js?
To me, that's the real amazing thing. You can compile dosbox to run within firefox compiled to run within firefox.
There's also a new innovation that we're on the cusp of... removing virtual memory.
Back when Microsoft actually did research, they found virtual memory induced a penalty of around 33%.
asm.js has a performance hit ideally around 50%. But here's the kicker... internet browsers are already virtual machines! So they don't need CPU virtual memory protection. So 100% - (50% - 33%) = 83% of full speed inside a browser with completely portable code! (If we can develop the tools to disable virtual memory protection as needed.)
Microsoft was even working on an operating system to do just that, called the Singularity project.
How much longer until we provide the Allegro DOS games on allegro.cc? 
Ya know, maybe Shaw's Nightmare will bring us back to DOS after all.
It was cool playing the original Scorched Earth for a while, but the sound didn't work and the mouse input was bugged (offset by about 30% or so of the screen width, so some controls couldn't be clicked). I tried Bust a Move also, but it wouldn't go beyond the title screen.
Dune 2, in your browser, complete with sound and mouse. It even supports saves.
I was playing stunts, and it looked like the leaderboard was public. Its a cool concept, like a massive, public arcade.