I will only list sites that I consider to be reliable resources of information.
http://theacpa.org/default.aspx
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001463/
http://www.mayoclinic.com/health/fibromyalgia/DS00079
http://www.fmaware.org/PageServerded3.html?pagename=fibromyalgia
http://www.fmpartnership.org/- This one I am finding particularly interesting since there are several articles that are written by doctors that validate the syndrome.