How about this, take a board, say 2ft x 2ft. Mount it in a parallel plane to the ground. Place a metal ball bearing on it, have a metal circuit tilt the board to keep the ball from falling off the board.
That one would probably be pretty involved, if it's too complex, try something simple like have a wand with a tilt type sensor in it, have it connected to a string of LEDs, the more you tilt the wand, the more LEDs light up.
I guess we just need to know more about what you mean by "tilt"