Firstly this only works in survival. You need to take damage. For some reason, taking damage re-calibrates the server-client communication on where the client is. This means that standing on a ghost block will just increase your velocity (as you are falling) but as soon as you take fall damage, it will re-calibrate your location. Doing this on a slime block will just keep bouncing you up and up. Here is a video I made on it.
https://www.youtube.com/watch?v=PiHz4gVWnTQ
And here is a video on a practical use for it: https://www.youtube.com/watch?v=sFAlX7TKz1s
So yeah.
Thanks to Panda and Spire for helping me with the elevator.
I have known about this glitch for months, but I have been too lazy to do anything about it.
Is this still an issue in the current Minecraft Snapshot 15w47c or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.