Description Language for Taxonomy (DELTA): a method for encoding taxonomic descriptions for computer processing that an be used to produce natural-language descriptions, conventional or interactive keys, cladistic or phenetic classifications, and information-retrieval systems.
Integrated Taxonomic Information System (ITIS) Taxonomic information on plants, animals, fungi, and microbes of North America and the world.
ION - Index to Organism Names
NCBI - National Center for Biotechnology Information (a taxonomy browser for genetic information on malocostracan crustaceans)
Zootaxa - an online journal that publishes papers on animal taxonomy
National Science Foundation (NSF): Directorate for Biological
Sciences – Systematic and Population Biology
Southern California Association of Marine Invertebrate Taxonomists (SCAMIT) Homepage
National Benthic Inventory - National Benthic Specimen Collection
Hennig Society
Systematics Association

An Essay on Biodiversity and Taxonomy by F. Boero
Census of Marine Life
Global Biodiversity Information Facility (GBIF) - provides rapid and free primary data about biodiversity to the global scientific community;
National Center for Biotechnology Information (NCBI): Taxonomy Homepage
Tree of Life Web Project (TOL)
Species 2000
Centre for Marine Biodiversity (focus on northwest Atlantic)
OBIS - Ocean Biogeographic Information System - a database of global marine animal and plant distributions
Biodiversity Heritage Library - provides access to historical or obscure taxonomic literature

Polychaetes of Chesapeake Bay and coastal Virginia
Ceph Base
The Crustacean Society (TCS)
FishBase
Octocoral Research Center - California Academy of Science's website for octocoral taxonomy
Tanaidacean Homepage
World List of Isopods
Echinoderms of the South Carolina Continental Shelf
Sea Slug Forum

- Benthic fauna of Gray's Reef National Marine Sanctuary (located in the South Atlantic Bight)

Classification of Recent Crustacea (from An Updated Classification of the Recent Crustacea, Martin & Davis, 2001)