A classic game from the 16-bit era, someone has recreated Rick Dangerous in all it's glory (looks just like the Atari ST version!) in flash for your web browser! Just go here:http://rickdangerousflash.free.fr/ to play!
Another old game emulated online, Sango Fighter! Not as classic as Rick Dangerous, but I remember numerous duels against Hawkeye, shouting "Bugs in your eyes!" and "I will die young!" (as that is what the chinese sounded like to us). Play it here: http://www.classicdosgames.com/online/sango11.html. Note that it is actually emulating an old DOS PC, and automatically loading the game. I didn't hear any sound when I tried it.