These forums, of course!

And Nexus for the latest mods. I used to be active on their forums but not so much these days.
For gaming news I check http://www.pcgamer.com/ and http://www.rockpapershotgun.com/ every day. They both cover PC games exclusively, so I don't have to scroll through irrelevant stuff because I don't own a console. They also both cover a lot of indie games, mods and other PC gaming related news.
For youtube there are 3 channels I follow: Totalbiscuit (Totalhalibut actually, I don't care for the Starcraft 2 stuff) , Jesse Cox (channel is called OMFGCata) and the Yogscast. They're all gaming channels, but there isn't much overlap in the type of content they provide, unless they're doing a collaboration.
And http://xkcd.com/ is my home page. Usually nice comics, even though I don't understand most of the ones related to mathematics, physics, chemistry, etc. It's a simple page too so it loads quickly.