Those of you familiar with The Legend of Zelda - Majora's Mask know what the 3 Day Challenge is (also referred to as the 6 Day Challenge since the actual first 3 days you have to spend as a Deku Scrub). I've watched a couple of videos of some guy actually doing this.
http://www.youtube.com/watch?v=o2cwJu_Vvp8&list=PLA3D8FE36217D08DEInteresting enough, he did reached Clock Tower at 8:36 PM on the second day which means he barely took more than a day and a half (obviously with slowed down time). I always loved MM for its rich a different feel than other Zelda games. A 3 Day Challenge always sounded like way too much for me. But after watching this guy, it doesn't seem so impossible anymore. Sure, I would be playing using an emulator and I'd probably not do some of the crazy stuff he did to speed up (well, not THAT crazy, but pretty impressive that he thought of it), but I'd still like to try. The only real sticking point would be to make it to Romani Ranch before 6 PM on the first day to get Epona (he managed to get there at 3 PM-ish). Everything else doesn't seem to be much of a problem as far as I noticed. So I might actually try the 3 Day Challenge at some point. If I do, I'll be sure to let you know how it went. I'll be obviously using this playthrough as a reference, especially since it cuts down research time of a few necessary things and the order in which to do things in order to get it done.
I already did the 3 Hearts Challenge in Ocarina of Time on my actual N64. IDK how many times I've played through that game, I just know that at one point (years ago) I just wanted to try to beat the game without collecting any Pieces of Heart or any Heart Containers. I did use bottles and fairies obviously, but it was still a nice challenge.