I've collected together some of the websites that I've found most helpful while researching and writing my books.
Some of these are really well put together, well-written, and fun, and might help you get to grips with some head-scratchy science concepts.
Everything you need to know about chemical elements
The best elements videos bar none
Secrets of the briny deep
Particles, forces and bosons ... oh my!
All the best, unbiased biographical info
The Miller Centre (Uni of Virginia)
Other Great Sites
Best of the rest
Discovery Channel's Curiosity Corner