What invention would you choose?

Question:

What invention would you choose?

I'm interested in great inventions that haven't been invented yet - what would you choose if you could have ONE invention created for entertainment purposes that is not yet in existence? (can be taken off Sci Fi movies etc)
P.S I have no idea which catagory to put this question in!

Best Answer - Chosen by Asker:

The guys at work have been talking for a long time about a Glow-In-The-Dark Hackey Sack. We always run into the problem of not being able to play once then sun goes down so it would definatly help out.