Mashable

I can't say enough good things about Mashable.  I'm a fan on Facebook and follow most of their channels on Twitter.  I learn about all the hot new social media sites, mobile apps (Grouped In anyone?), SXSW, technology in education (so great!),  technology for good, startups, web apps (Schedulicity is a new favorite) and so much more.  I swear they're responsible for most apps on my phone and making my life much easier and much more organized.  I also love their articles that are specifically written for marketing and businesses.  Very readable and entertaining.