ScienceDaily. If you want to be a complete science nerd (and that's cool these days) you can make it your homepage because it changes constantly.
You can search the site to find recent science news on topics we have covered. For example a search on 'Panspermia' would lead you to three articles and this one, Evidence Of Liquid Water In Comets Reveals Possible Origin Of Life, from 2009 looks interesting. Remember that this is a news site though, so remember to follow the links back to the original article, here Liquid water and organics in Comets: implications for exobiology.
You can also just browse the site by topic to see what catches your interest. So for this week's topics you might want to browse The Origin of Life or even Extrasolar Planets.