Ignore the fact that this page looks like it was made in 1995, because the content on it is quite relevant. It contains a list of over 100 factors that effect your ranking, either positively or negatively in Google (and they don't hurt your standings in other search engines).

ClickZ has a good article on how HTML Validity affects e-mail deliverability.

The article points out that AOL is checking for valid HTML in email messages, and will reject mail with a 554 HVU:FO error response.

AOL HVU:FO Error:

Who ever came up with the pricing on the iPod models is a genius. I was talking to a friend yesterday who was shopping for iPods. He was saying how he has no idea which model to get, because the next model up always offers more storage with a better price/storage ratio.