National Geographic has a terrific section on the site that's dedicated to daily nature and science news and headlines. The section showcases a variety of content such as news, blogs, photos, and videos. The superb images and outstanding writing that define National Geographic are present in full force, making the site a great place to spend time. Lots of it. =)
There are a few other sections that are worth a visit:
- Daily Cultures News
- Photography (including photo of the day)
- Weird News
- News Watch
- Jigsaw Puzzle Generator
and the Education section, while still very much in beta, looks promising.