From Brian Krebs comes the story of the fall and rise of internet hosting firm HostWinds. Founder Peter Holden explains how they came to get enticed into hosting spammers, which seemed very profitable in the short term, but turned out to not be so tenable for the long haul.
Interesting to note: A Spamhaus listing is one thing, but when AOL says they're not accepting any mail from anyone on your network any more, that really drives the clients away.