Found this tutorial for making a MaKeyMaKey style shield for a Shrimp style Arduino board:
http://fromscratched.nl/index.php/shrimpkey-maak-je-eigen-makeymakey-deel-1/?lang=enThe ShrimpKey is almost capable of the same things as a MakeyMakey.
There are three differences:
the ShrimpKey has 9 connectors (MakeyMakey: 18)
the ShrimpKey can only type letters (MakeyMakey: can move the mouse also)
the ShrimpKey will cost you around $ 7 (MakeyMakey: $ 50)
OK, there is a fourth difference (and I find this the most fun and important one):
the ShrimpKey is DIY (MakeyMakey: off-the-shelf)