What about the cheat for Alex the Kidd in Miracle World cheat, when you have no lives left but have over $800 you press up on the control pad and press button 2 eight times. This will let you continue with the game.
Although I only got this cheat after I had finished the game already
the cheats i remember the most aside from the contra cheat were in super mario bros.
the first one is in level 1-2 - at the end of the stage, instead of going into the pipe you take the elevator and jump on the roof to find the warp pipes.
the second one - i can't remember the level, but you can get 99 lives on the steps where the beetles come down by hopping on them repeatedly while staying in place.
007-373-5963 : To easy, thats from Mike Tyson's Punch out. It takes you straight to Mike Tyson, whom I may add I mastered kicking his ass as a kid. It was to the point where I'd win like 20 times an hour.
Mario Cheat: level 3-1 jump on the turtle shell, the best.
I know a lot of nintendo games would let you continue if you held down select while u continued.
I remember A trick from the first mario level where you did something and it would send you to all hidden water levels. Also there was the trick where you stepped on king Kuppa's nose at the same time as you landed on the hammer you would start the next board as the small mario but you could shoot fireballs.
IDDQD and IDKFA were from Doom. I couldn't remember what the hell they were from for a while but now that you said that it came back to me. I think it was for unlimited ammo and so you couldn't die.