Oceanography

ASLO - American Society of Limnology and Oceanography
NOAA El Nino - Site provides a wealth of information about La Nina and El Nino
NOAA - The National Oceanic and Atmospheric Administration
PMEL TAO Project - The Pacific Marine Environmental Laboratory's Tropical Atmosphere Ocean project
AGU - The American Geophysical Union
NSF OPP - National Science Foundation's Office of Polar Programs
DataStreme Ocean - An educator enhancement oceanography course.
EnviroAir - A listserv on acid rain, air quality standards, etc.
Antarctic Bilbiography - Access to the polar regions literature.
SOLAS - The international surface ocean lower atmosphere program.

Chemistry

Periodic Table1, 2- Valuable information regarding the periodic table
Photochemical Society - Information regarding the InterAmerican Photochemical Society and companies that sell photochemistry supplies
IUPAC Photochemistry - Glossary of terms used in photochemistry (pdf)
MSDS - Information regarding Materials and Safety Data
ACS Environmental Chemistry - American Chemical Society, division of Environmental Chemistry website.

Miscellaneous

USGS - The U.S. Geological Survey
On Line Maps - Information on how to create maps interactively
NASA - The National Aeronautics and Space Administration
Environmental Fate Database
Ozone Depletion and Warming Potentials
EPA Global Change - EPA global change research program.

Students

REU Program - Research Experience for Undergraduates.