Thanks to SmallBusinessBrief.com for tipping me off to this article.

Just like in traditional brick-and-mortar stores, libraries, parking lots, and amusement parks, you need to post notices and policies on your Web site that govern the use of materials, services and goods from the site.

A Terms of Use Agreement acts as a contract between you and the people who visit your site. A carefully worded agreement can protect your company from liability, and should address the key terms and conditions for the provision of information, goods, or services. The agreement should be conspicuously displayed and available.

Read more on Website Terms of Agreement