I'm sure I've already bragged about this before on this site, but there is no one in the world better than me at Super Mario World. I played it so much that I can just fly around in the air and know when to drop down to hit a single turtle on any level and bounce right back up. People who have watched me play it don't believe their eyes, because the way I play it is patently absurd. I have reached the point where I just completely ignore the layout of the levels if that makes sense (like jump from here to get to there, etc.) On the first level of the second land, when you go into the pipe and the sky has like 3 long rows of coins, I have the ability no matter the time of day or how fucked up I am to fly perfectly and nab one row at a time without touching a single coin on another row. I can do it to the middle one too, without touching the top or bottom row of coins. We did a challenge where I was only allowed to be small mario via purposefully running into the first bad guy if I wasn't already small, and I still jumped around and bounced on turtles like I had a cape on - never dying once.
One of my friends still just likes to watch me play it for hours. What's funny, though, is he is an absolute master at Megaman X2 for SNES which I believe is infinitely harder than Super Mario World. He never dies and he gets every single secret including that tiger uppercut thing that is almost impossible to get unless you are superhuman. In Super Mario World everything is totally intuitive regarding the controls and the physics. One of my favorite things to show off is that I already have like 50 lives before the end of the second land, and obviously 99 when I get to the top of the cave land in that level where the spiky guys turn into silver coins.
I'm especially impressed with people who have mastered mario 64, though, since to me mario world is like playing on god mode without having to enter a cheat code.
I just got a DS and and am trying to master New Super Mario brothers. It's pretty awesome but nothing will ever compare to Mario World. Although I heard Galaxy pretty much owns. Don't ever see myself buying a Wii, though, unless someone gives it to me for $50. Even with my being a squaresoft fag, I must admit that Mario RPG is boring as hell. Mario 64 pissed me off because it didn't have any real magic to it like Mario World, although it would be nice to master the art of flying in that game. Mario 2 is very satisfying to beat. Mario 3 is of course awesome because of all the neat little secrets.