Below are links to websites with information about invasive species. 

United States Department of Agriculture Invasive Species Website
http://www.invasivespeciesinfo.gov/

Center for Invasive Species and Ecosystem Health
http://www.invasive.org/

United States Fish and Wildlife Service Invasive Species Program
http://www.fws.gov/invasives/

United States Forest Service Invasive Species Program
http://www.fs.fed.us/invasivespecies/index.shtml

Bugwood – a collection of information and photos on invasive species
http://www.bugwood.org/

All Taxa Biodiversity Initiative (ATBI) –information on parks collecting data on species within their boundaries
http://www.atbialliance.org/index.shtml

Center for Invasive Plant Management
http://www.weedcenter.org/index.html

United States Geological Survey
http://www.usgs.gov/

Natural Resource Conservation Service
http://plant-materials.nrcs.usda.gov/technical/invasive.html

Discover Life in America
http://www.dlia.org/