h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

This might not be much use as a trick unless you can think of a way to polish it up and turn it in to an illusion...maybe involving cloths or screens, anyway, here goes.
To balance an egg on it's wide end set it on a little spread of salt. You might have to adjust it a few times to make it balance, but the salt gives it something to balance on. Blow the salt away and usually enough grains remain to keep it balanced.
I don't want to start a big debate but I have heard tell that this, and other rough surfaces, is how the eggs balance on those "special" days that some people believe occurs at equinox and is the only time eggs balance. I am a bit vauge on the sunject but I think some followers of various beliefs have special egg balancing days.

On the subject of eggs,

An interesting "trick" is to give someone a box of eggs, of which 1 is boiled and the remainder fresh and challenge them to find the boiled one without breaking them.

The way to do this is to spin the eggs on their tips. The fluid in the fresh eggs slopps around & prevents it turning. The boiled egg however is solid and will spin on it's end like a top.

Easy when you know how

Ugi

mmm....omlette....