Via BoingBoing, there's a free science fiction writing guide available online. From the guide site:

"Have you always harbored a secret (or not so secret) yearning to write? This course is designed to help you learn many of the skills you need to write successful science fiction and fantasy stories. You can use the skills you'll learn here in other kinds of storytelling, as well."

This looks like a great resource-includes deeper dimensions writing, world building, human characters, aliens, and much more.

Related: If you're in the mood for science, you might want to check out Scirus, a science search engine.