An Illustrated Herbal - http://www.magdalin.com/herbs
 - contains a compilation of around 500 plants and their
corresponding therapeutic properties - for everyday use.

 HerbMed - http://www.herbmed.org
 - an interactive, electronic herbal database

 PubMed - http://www.ncbi.nlm.nih.gov/PubMed/
 - service of the National Library of Medicine,
includes over 14 million citations for biomedical articles back to the 1950's