koan - 6:17 am on May 18, 2011 (gmt 0)
I had a fresh new site that was crushed like that, some person decided to put it in the footer of his real shady/spammy network of blogs for some reason (when I think of it, right after someone offered to buy the domain for a low price and I refused). A few weeks later, the site stopped getting any Google traffic and I let it die. It never recovered, the idea was rather weak anyway and I didn't work on building links and such, I had other projects. Still, I had my evidence that others *can* influence negatively your rankings, but it's never 100% certain.