Here's an SK-5 from Highly Liguid who also sells these midi retrofit kits
Alien Devices have a couple amazing a couple Amazing Angry Lookin SK-5's with info and sounds
Here's one from Tablebeast
Here's one from Oscillateur.com This site has a helpful "Getting Started" circuit bending section too
This is Tony Mason's SK-5 Page. There's an SK-5 Manual on this site if you need one
Here's a link to an SK-1 Midi Mod(pretty advanced for me), might be simiolar to an SK-5?
Here's another