Well at least its presence on the Internet. It appears to be gone and I can't locate the .XLA file anywhere to save my life. I wrote about this neat little Excel add-in a long time ago in my Genetic Algorithm Excel Addin post and since then its remained amazingly popular. I sure hope the developer reposts it soon but I'm not holding my breath.
FWIW, I actually bought this XLA from the developer because I wanted something to poke around with in Excel without building something in Rapidminer. Of course you can do the same in Rapidminer, but I'm a tinkerer and a poker and this satisfied my curiosity. :)
UPDATE: The Genetic Algorithm Excel Addin is BACK! The developer moved websites and uploaded it back online again! Thanks Noyan!