Aside from books, dominoes are Mister Finn’s favorite toy. They are scattered around our house in a fashion that could appear meaningful, like abstract mathematical equations.
He taps them together, pleased with the sound. If we bring two with us when we go out, they will keep him amused for a long time. (Which in baby-time is about 7 minutes.)
He uses them to touch other things around the house, too, like Winnie and the DVD player.