I discovered EarthPortal via an intriguing post by John Wilkins. They describe themselves thus:
The Earth Portal is a comprehensive resource for timely, objective, science-based information about the environment. It is a means for the global scientific community to come together to produce the first free, expert-driven, massively scaleable information resource on the environment, and to engage civil society in a public dialogue on the role of environmental issues in human affairs. It contains no commercial advertising and reaches a large global audience.
My first impression is very good. Lots of interesting content (all creative commons licensed), good presentation, RSS feeds. If you’re interested in environmental news, go take a look.