Drugs.com http://www.drugs.com
Online drug information in an A to Z format. Includes information about clinical trials, latest news, drug interactions, and a pill identifier.
Drugs@FDA http://www.accessdata.fda.gov/scripts/cder/drugsatfda/
A searchable catalog of FDA approved drug products both prescription and otc. The databse includes information such as therapeutic equivalents and links to documents relating to approval.
Electronic Medicines Compendium http://emc.vhn.net/
This site provides the UK approved information sheets for prescription medicines. It is the up-to-date, official and comprehensive source of information about medicines prescribed in the UK.
Farmamondo.com http://www.farmamondo.com/
Provides pharmaceutical information to Health professionals but can be of interest to the public as well. It provides instant information on some of the most innovative recently released international medicines, the moment they are put on the market anywhere in the world, and makes possible their immediate distribution.