I have very good memories of playing Mario Bros. with one of my best friends when I was little. I had this really old video game player that half the time never worked and we used to play Mario for hours. She always was Mario and always knew the cheats, and I'd be Luigi and die within a couple minutes.
We sold the old player years ago and ever since I never played that old Mario game again.... until I recently found it online! I was so happy, it brought back so many memories.
Anyway, it's very old and the sound is really messed up (push the 'S' button on your keyboard to turn it off), but I find this game seriously addicting:
http://www.breumelhof.nl/nintendonly/supermariobrothers.htm (Key 'X' makes you jump, the arrow keys make you move, and 'Z' makes you run fast)
Has anybody else ever seen this version? I know it's old, I have no clue where I got the game when I was little, but it's really fun.