I also use www.allaboutexploreres.com as an example of website that looks professional and has all the information needed to give a successful evaluation.  Once the kids start reading the information, especially on Christopher Columbus since they are more familiar with him, they start getting suspicious; links to actual real sites are included.  If you have not used this site it was created by a teacher and a librarian, in PA, to help teach website evaluation.  It is an awesome teaching tool.