Images of the Dry Tropics - http://hoya.mobot.org/gradstudents/olson/drytropics.html
Photographs of plants, animals, and landscapes from dry tropical habitats in the Americas, Africa, Madagascar, and Asia. Dry tropical habitat types include tropical dry forest, tropical deciduous forest, thorn forest, spiny desert, savannah, cerrado, and caatinga.

Images of the Dry Tropics - http://www.explorelifeonearth.org/drytropics.html
Photographs of plants, animals, and landscapes from dry tropical habitats in the Americas, Africa, Madagascar, and Asia.

Len Webb Ecological Images Collection - http://www.gu.edu.au/ins/collections/webb/
Photographs by ecologist Len Webb depict a wide variety of native vegetation, fauna, landscapes, and soils, mainly in tropical and subtropical Northeastern Australia. Represents a wide range of ecosystem types.

Millennium Assessment of Global Ecosystems - http://www.ma-secretariat.org
International project and process designed to improve the management of ecosystems and their contribution to human development by helping to bring the best available information on ecosystem goods and services to bear on policy and management decisions.

Terrestrial Ecoregions of the World - http://www.nationalgeographic.com/wildworld/terrestrial.html
Maps, descriptions, and index to 687 ecoregions across the globe. Javascript required.

The Buell-Small Succession Study - http://www.ecostudies.org/bss/
A long term old-field permanent-plot ecological succession study on the New Jersey Piedmont.

The State of the Nation's Ecosystems - http://www.heinzctr.org/ecosystems/
Online book about the current status and trends of the environment of the United States, aimed at public policy makers and concerned citizens.

The World's Biomes - http://www.ucmp.berkeley.edu/glossary/gloss5/biome/
Introduction to aquatic, desert, forest, grassland, and tundra biomes. School class project.

World Wildlife Fund - Ecoregions - http://www.worldwildlife.org/ecoregions/
Detailed descriptions and images of the world's ecoregions. Javascript required.

WorldBiomes - http://www.worldbiomes.com/
Covering five of the major world biomes.