LightBlueYoshi/Y05H1 found a few cool tricks for this game:
http://www.youtube.com/watch?v=cbwCweVSVeQ&feature=channel
Copied from video description:
'Instant Speed Drop:
Really helpful for turning around! By ducking for one frame and jumping on the next, you can immediately drop your speed to 12.
Pipe Boosting:
Some pipes release you one tile below the top of the pipe. You're allowed to boost yourself on these pipes (as long as you're coming out from the bottom). The first frame you're able to gain control, jump. When you jump, moving to the left or right for the next two frames will boost you in the opposite direction! In some places (like in the one at 0:24), you can go into walls. This is probably why the game designers made sure that most pipes were extended at least one tile above the ground...
Infinite Jumping Glitch:
This isn't exactly infinite, since every jump requires one egg. When you throw an egg in one direction, holding in the opposite direction right after Yoshi's throwing animation is finished will cause him to act like he's on the ground for two frames. You're allowed to jump on those frames - even when falling! Vary when you want to time your jump by timing your egg throw. Keep in mind, though, that you have to jump on the first frame. Otherwise, if you jump on the second frame, it, for some reason, doesn't allow you to jump the next time. (Skip to 1:06 to see it used 6 times in a row!)'
