balance

How to balance an egg on its end with no visible means of support:

You need just a few grains of salt.

Make a tiny pile of salt on a flat surface and balance the egg on the pile. Then carefully blow away the excess salt, leaving just the few grains actually supporting the egg. (Obviously this needs preparing in advance - if pressed to repeat the trick, place the egg down hard enough to break the shell, which will also enable it to balance).