Play your favorite Nintendo Entertainment System games online with vNES.  They boast the largest online collection and have many of your favorite titles.  How about a round of Super Mario Brothers or MegaMan.  I chose to play Marble Madness and Mrs Pacman but I'm sure your favorites are listed.  Controls are simple, arrows keys to move, Enter key for Start and Z/X for action buttons.  If controls don't work right away, simply double click on the Java screen.  Enjoy it while it lasts, it can't be legal.  If it is, maybe the owner can explain to us how he's doing it without Nintendo riding his, or her tail.