Hell, what about memories?
Someone might want to scrub their presence from the net, but if you make a right ass of yourself, it's hard to erase that from the wetware in people's skulls. Someone might even blog about it - or worse.
For example, about a month ago, one not-so-gentle-man by the name of George Tierney decided to get into a Twitter war with Sandra Fluke - the same woman who testified to US Congress about the Pill, why women take it, and why it should be covered by people's health plans [1, 2]. George started calling her rude names and four letter words beginning with "c". Other people took offense. Then he demanded they remove their observations. A small Twitterwar ensured, where he insulted many people, including Glenn Danzig at one point.
While the dude was a major league asshole, he probably had a few mental health issues, starting from anger mismanagement, and going up from there. Regardless of whether he deserves his presence to be scrubbed from the Net or not - it would be impossible to do so in the near future, because people will remember what he did. Ms. Fluke has grace enough to put it behind her, but a lot of her defenders weren't that generous. Perhaps in 10 years he'll be a footnote. This year he's a teaching moment for teachers:
http://www2.wspa.com/news/2012/may/23/upstate-mans-tweets-go-viral-real-world-impact-ar-3845986/
[1 In the absence of a NHS, of course.]
[2 I should point out that women don't just take the Pill for better sexytime, but - surprising as it may seem - ALSO as a health measure. While I think it would be redundant to educate the sophisticated, urbane, and worldly El Reg commentariat on this (especially females), I just want to prevent any "Rush Limbaugh" moments, if you know what I mean.]