Michael Scott points us to a story of a woman who not only drove from Maryland to California to go to Facebook's offices to complain about having her account banned, but (when that didn't get the account reinstated) then she sued the site for the ban. Facebook says she was banned for harassing others. The woman, Karen Beth Young, says she was just promoting causes she was interested in, and, in doing so, friending lots of people (about 4,000 by the time the account was closed). She claims the ban violated her constitutional rights... and the Americans with Disabilities Act.
The constitutional claim is almost certainly a non-starter. As a company, Facebook certainly has the right to ban pretty much anyone it wants to ban. The ADA claim also seems like it won't go very far, but as Eric Goldman notes, with so much ADA litigation, there's always a chance that "a court could have sympathy for the plaintiff." In this case, she's claiming that she has a bipolar disorder, and Facebook "does not provide reasonable accommodations to individuals with disabilities," like her. But that implies the problem was with her mental health issues, rather than her actions on the site. This seems like yet another case of someone saying that if they don't like something it must be against the law... even when that's not the case at all.