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.php
Visual Elements: The Halogens - Overview, general properties, and chemical data for the group. - http://www.chemsoc.org/viselements/pages/data/intro_groupvii_data.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