I think the best thing a small business can do is invest a small sum into buying a domain and getting someone to design their website where fans can become members independent of Facebook, MySpace, Bebo, etc. Then use social websites as a way of adding on, rather than relying on one as their only or main means of advertising or getting fans.
With a domain, unless you are suspect of large copyright infringement (e.g. linking to movie downloads), chances are that you'll get several warnings about an individual copyright infringement before the website is shutdown, where as I'm sure with Facebook, someone who complains about their work being used such as a copyright background image will result in the account being suspended. Even if a paid hosting account is suspended, I'm sure it is easier dealing with the hosting provider's support than Facebook support, especially when you're a paying customer.