Brett Borders wrote a great article on the 13 pages negative online publicity comes from that are most difficult to outrank, which includes articles on authority blogs, government pages, press releases, off-topic pages, and rip-off report listings. Are there more? Probably. On Sphinn, a user suggests that this beginner guide on reputation management should be applied, and here are some suggestions: don't open 100 blogs, don't start a MySpace account, don't start a Wikipedia page, and more.
Personally, given that I just scored Andy Beal's new book, I suggest reading his 7 step online reputation crisis plan which realistically gives you steps to identify and respond to reputation management crises. (btw, he's giving away an iPod Touch. I claim it.)
Forum discussion continues at Sphinn.