A smattering of science websites I like:
What if? physics questions answered by the folks at XKCD: http://what-if.xkcd.com/1/ Includes “what if you had a mole of moles?”
Phys-Org – recent articles on all sorts of sciences: http://phys.org/
Discovery Magazine’s blogs; http://blogs.discovermagazine.com/
Various geology blogs: http://blogs.scientificamerican.com/rosetta-stones/
En Tequila Es Verdad: http://freethoughtblogs.com/entequilaesverdad a blog of a only technically amateur geologist who got me loving geology again with her passion about the silly rocks.