Here's a fairly simple homebrew game from littlevish that reads your mind. The Magic Number is coded in LUA and basically tells you which number you are thinking of.

David Blaine magic much, eh? It sounds pretty interesting enough for me as I'm all for those mind tricks and whatnot. It may seem boring playing it by yourself, but you're sure to get an audience with kids. As littlevish notes, "little kikds seem to be particularly impressed by this trick."

Not hard to imagine why. If you even wanna go so far as tricking your nieces and nephews, or that kid you're babysitting, you can even bet with them that you can figure out what number they're thinking of. Yeah, that would be mean, but the look on their face when you get it right would sure be priceless, yes?