American Geophysical Union (AGU) is the world's largest orginization of Earth and space scientists. They recently launched a section in their site dedicated to a network of science blogs. Their ABOUT section explains it all.
I was honored to be asked by AGU to create the banners for the blogs. Click the image to get to the AGU Blogosphere site. Scroll down and click each mini banner to see the full banner. It's worth spending some time reading through the blogs, too. They all have really fascinating information in them.