If you read my previous post, I told you about I Write Like, a site that analyzes your writing samples and compares your writing to that of well-known authors. A few people have asked me some questions, so allow me to go into a little more detail.
At the very least, the site is not just a random rotation of authors. The same writing samples will get the same results. I've tested this time and again.
Also, I think that there may be something to whatever algorithms they use. When I post writing samples that are similar in content (e.g. passive or descriptive parts), I get different authors then when I post action or dialogue sequences. By the same token, when I posted a short story about monsters from another dimension, I got Lovecraft.
I get Stephen King more than any other writer, and this stands to reason. Not from a success or skill standpoint (yet *wink*), but from a style one. He's my favorite author, and the one I've read most by far, so incorporating a lot of his style into my own is almost expected.
Lastly, as a goof, I posted the first line from King's The Dark Tower, saga, and got King. I grabbed a sample from Twilight, as well, and got Stephenie Meyer. Same for Fight Club.
The more I think about it, the more I think that there's at least some degree of accuracy, although your mileage may vary. In some cases, you may not like with whom your writing compares, so be prepared for the horror. :-)