If not an employee and you do not have a valid work made for hire agreement, you will need to license the content. The questions you need to ask initial relate to how you intend to use such material. Do you want to use such material merely on the web site or do you contemplate usage in other media, such as off line, hard copy uses, or in other manner of use such as in marketing and promotional materials, as but some examples. Read The Need for Vision and The Permission Form. If so, read Screen Shot Liability for Computer Book Authors.
Many sites have chat rooms or other forms of content provided by visitors to the site.
If not, your rights in the site may be put at substantial risk. Under certain circumstances, domain names can be trademarked. Read Domain Names and Trademarks. While generally linking is not a problem, if you have linked in such a manner as to potentially infringe on the linked site s rights or have implied endorsements from the linked site to yours or in some other manner created potential liability issues by virtue of the linking, this must be examined. There is a growing set of legal issues dealing with infringement claims by these tags and keywords.