For me, if I'm scrambling for new ideas, one of the first places I go is io9. io9 has great articles that touch on all the best geeky things--where else can you go to find an archaeological article on a purse that's 4,500 years old and decorated with dog teeth? Or learn about tornadoes in the sun? io9 has it all, from science to pop culture, from the truly weird to the informative.
If I just want something funny and quick, I usually go to Dropping the Science on Memebase.
The Mary Sue is the best of both worlds--it often has the interesting/weird/awesome news articles like io9 has, but will also have the hilarity that I find on Dropping the Science. With a refreshing feminist bent, The Mary Sue consistently delivers news that I actually care about (new Doctor Who t-shirts? Yes, please!), and news that the world cares about (they are adept at critically examining pop culture and geek works for race fails and gender fails. But I'd be lying if I didn't say that my favorite thing about The Mary Sue is the series of reviews by Amanda. Go on. Just click the link.
Two months ago, and I might have laughed if you'd suggested Pinterest as a source of nerdiness. I thought it was just for crafters! But boy, have I changed my tune. Pinterest is a fun, quick, easy way to get new ideas, find awesome art, and discover inspiration. I definitely suggest checking it out. To get your started, you can check out my board entitled "Geek Awesome" :) You can also see my boards on "Across the Universe" and another board I've made just for the next project I'm working (even though it's secret for now!).