I don't recommend you try these unless you can deal with failure and frustration particularly well. These are extremely hard to pull off consistently, and it takes time to master these.
Basically what I'm doing here is called the Phantom Grab.
The gist of it is that I collect an item with the boomerang, have it follow me to a specific frame, which then spawns another item into the boomerang. The reason this happens is that when an item is collected at the same time as the game spawns another item into the screen, the game gets confused and accidentally spawns the item into X's boomerang, instead of its regular spawn spot.
This is frame and pixel perfect.
These tricks are:
Booty Grab: Allows me to collect the subtank in Armored Armadillo's stage without turning around and going behind the giant crushing machine.
Mammoth Sub Heart: Allows me to collect the subtank and heart tank on Flame Mammoth's stage simultaneously, without having to go down to the frozen lava to collect the heart.
Waterless Jump: The trickiest by far, but absolutely makes you feel like a badass once you get the hang of it. This allows me to collect the Sting Chameleon heart tank without the water from beating Octopus' stage beforehand, as well as without the use of the ice sled. In order to do this trick, one also needs to be familiar with a technique called juggling - in this case juggling the health pickup in such a way that it doesn't catch up to you before you're ready. This takes practice, and even then it's easy to screw up. The jump is really precise because you need the heart collect to be close enough to the peak of your jump, so you can still turn around and get back to the platform without dying. Tricky.
Magic Carpet: This trick allows me to spawn one of the moving platforms in Storm Eagle's stage to fly me across the stage. This is the easiest Phantom Grab to do, but actually flying with the platform takes practice. Ideally, you want to use it to grab the Subtank with your boomerang, jump back on it, and have it fly you to the Dr. Light capsule.
It took me a lot of work, blood, sweat, and tears to get these down, but I can do them on a somewhat consistent basis. Waterless being the most difficult, as I said, due to the number of moving parts. The other three I can pull off pretty much every time.
I bet 
