Memory Tests and Music

In my continued quest for intellectual stimulation, I began a search for online memory games - you know, flip over two cards, memorize their positions, find the pairs. There are a few different ones out there of varying degrees of difficulty (and it is easier once you memorize the designs on the cards), but one in particular intrigued me. One website has a piano tone version of the memory game. Instead of seeing any sort of picture, you get the same image every time, and what you memorize and match are the sounds - the piano tones - that play when you click on a card. It's the first somewhat difficult game I've found, and probably very useful if you want to have good musical memory. Either way, it's different enough to be interesting once or twice if you like a challenge.