Local and State:

Association of Chemical Industry of Texas

Blueprint Houston

Citizens Environmental Coalition

City of Houston

Clean Water Clear Choice

Galveston Bay Foundation

Greater Houston Partnership

Harris County Citizen Corps

Houston-Galveston Area Council

Houston Geological Society
Houston Tomorrow
Shell Center for Sustainability of Rice University
Subsea Oil and Gas Directory (List of Oil and Gas Companies in Houston)
Take Care of Texas
Texas Chemical Council
Texas Envirothon - University of Houston Clear Lake Environmental Institute of Houston
Texas Land & Mineral Owners Association
Texas Nature Conservancy
Texas Oil and Gas Association 

Regulatory:

Harris County Flood Control District

Harris County Environmental Public Health
(PHMSA) Pipeline and Hazardous Materials Safety Administration Emergency Response Guidebook

Pollution Prevention Resource Exchange Page

Railroad Commission of Texas

Texas Commission on Environmental Quality (TCEQ)

TCEQ Public Notices - search site
TCEQ Webcasts

Texas Risk Reduction Program

Texas Department of Transportation

United States Environmental Protection Agency (EPA)

US EPA Region 6

Louisiana Department of Environmental Quality (LDEQ)

Resources:

Allen Wyatt's Excel Tips

Allen Wyatt's Word Tips

ASTM

Code of Federal Regulations

Electronic Code of Federal Regulations

FEMA Emergency Management Institute - Independent Study Course List

Environmental Data Services (ENDS)

Federal Register

Grinning Planet - Saving the Planet One Joke at a Time

Metric Conversions Online

Mr. Excel - Your One Stop for Excel Tips and Solutions

MSDS Search

OnlineConversion.com

Regulations.gov

RQ Calculator

Topographic Maps

WISER - Wireless Information System for Emergency Responders (new version available for download)

Partner Organizations:

Academy of Certified Hazardous Materials Managers, Buffalo Bayou Chapter

Air & Waste Management Association, Gulf Coast Chapter

NAEP

NAEP Chapters

Society of American Military Engineers, Houston/Galveston Post