It says so right on its 'Disclaimer' page:
I figured out that a word like "onomastomancy" could be coined from the "onomasto-" prefix and "-mancy" suffix, and sure enough, when I did a quick search at Google, I found that the word actually does exist with the meaning I had in mind. I don't have any idea how onomastomancy might really have been practiced in the past, and I don't really care to find out at this stage (although it might provide an interesting bit of obscure knowledge bring up at a dinner party). I loathe to think that charlatans who pass themselves off as medicine men and mystical sages deceive people by perpetuating all sorts of superstitions. I live on a continent where the majority of people ascribe to harmful beliefs in supernatural powers which, if they exist at all, could only be evil. Inspired by these primitive beliefs, people brutally beat one another to death, cut out their freshly slaughtered enemies' hearts and eat them, chop off children's genitals to make them into magic potion, and rape babies to cure themselves of AIDS. Just so that you don't misunderstand the satire:
The theory of onomastomancy expounded at this Web site is nonsense.Did you find any of it convincing, though? If so, it was because I structured it according to a specific technique of deception, and this should be a warning to you to look out for similar tricks practiced in many belief-systems. (I was a bit lazy to do it systematically, though, so if you saw through it all from the start, you are probably used to having to separate the wheat from the chaff.) Most people would not be easily taken in by a blatant lie told out of the blue: "Hi, Kelly, nice to see you! Oh wow! There's a big orange elephant perched on top of your head!" However, carefully blend the lie with a couple of things which your subject accepts as true, and you're well on your way to getting people to believe in orange elephants and onomastomancy.
http://www.alphabetickle.com/alphabetickle/onomastomancy/site.nsf/pages/disclaimer