DDoS Attacks for the Common Man:
"Ask not why the DDoS bell tolls for thee.

You might ask why you, who monopolized your industry or sued customers for using someone else's product, should be the target of a DDoS attack? You might as well ask why there's random street crime. The answer is that the Internet is a rough neighborhood, and even little guys have disgruntled former employees and customers who feel cheated, not to mention ex-spouses and competitors. Trust me, it really could happen."

Most Web sites don't have or need the resources that Microsoft or even The SCO Group put in theirs for normal business, and it doesn't take an army of zombied clients to bring them down. Just a few clients, focused on the job, can cause problems for a Web site. Froutan says that at his company they've seen such attacks go on for days at a time. Experience with the MyDoom worms certainly bears that out.…

http://www.eweek.com/print_article/0,1761,a=122636,00.asp