I've been trying to create a simple accessibility game for the visually impaired that uses audio tones to give clues on how to solve the puzzle. Lo and behold, today I came across a memory game that uses sounds instead of pictures.
It comes in four different sized grids, increasing the difficulty: 4x3, 4x5, 6x6, and 6x6 where the tones swap places with each other if it isn't a match. Here are a few thumbails of the game in action:
Click for full size images
Accessibility Game: Tone MemoryThe main menu
Accessibility Game: Tone MemoryI've just matched two tones so they are disappearing
Accessibility Game: Tone MemoryI got a match!
After you've finished, it tells you how long you took, your accuracy, and other things.
Now go give
Tone Memory a try on zefrank.com.
Also worth mentioning (though not specifically accessibility friendly) is zefrank's Animated Memory which has you matching animated pictures instead of just static images. 
