Here are some other blogs/organizations by Ent Army members:

Treecrusaders - a blog for kids who want to help the environment. A good place to send people you meet who are interested in helping nature:
http://treecrusaders.wordpress.com/

A website for preventing deforestation. Get information about issues surrounding deforestation and how to prevent it: 
http://nodeforestation.webs.com

And here are some other environmentally-related sites:

The Nature Conservancy:
http://www.nature.org/

Greenpeace:
http://www.greenpeace.org

PennEnvironment:
http://www.pennenvironment.org/

Schuylkil Wildlife Rehabilitation Center:
http://www.schuylkillcenter.org/departments/wildlife/

Sea Shepard (anti whaling and illegal fishing group):
http://www.seashepherd.org/