I voted Netflix because I looooooove my movies, but then I realized that "Google" was an option. I don't think there's any way to avoid Google being the most used online resource, since I use it to find directions, look up recipes, etc. So, Google!
Youtube for how to videos and music
Deviantart especially when looking into a new artistic medium or technique
Occasionally yahoo answers but it can have a ton of bad answers. Rarely use this one unless it comes up in google results
Hmm... I don't think people with social anxiety would make it very far if it weren't for the internet. I mean... before the internet you pretty much had to do EVERYTHING in person or in snail mail, which was still a pain in the butt because you had to deal with the mail man or the postal office staff.
On the other hand... I think it's given those same people an excuse to never enter the "real" world because there's so much you can now do from home. You can work, socialize, order things, research just about anything, apply for jobs online, etc. all of this can be done online.