just one thing..

[Tiberius]

I've done Ouija boards before. It's a load of fun, especially when you know how it works. Tiny movements in your hands (which get restless when having to stay in the same position for any length of time) help move the glass. The rest is down to group will. Most people predict the words in their head before they are spelt out. For instance, if the question asked was "What is your name?" and the glass moves to A, and then D, then R, most people by this point have the name "Adrian" in their heads and that group knowledge (though not shared openly) helps move the glass to the rest of the letters.