The Chemistry of the Halogens
Covers their properties, methods of preparation, general trends, the hydrogen halides, and oxyacids of the halogens and their salts. http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch10/group7.html
Doc Brown's Chemistry Clinic: The Halogens
Includes an overview, general properties, reactivity trends, and information about the industrial electrolysis of sodium chloride solution. http://www.wpbschoolhouse.btinternet.co.uk/page03/The_Halogens.htm
Visual Elements: The Halogens
Overview, general properties, and chemical data for the group. http://www.chemsoc.org/viselements/pages/data/intro_groupvii_data.html