According to the Nielsen research group’s provided data for January-October 2011, Google, Facebook and YouTube are the most visited web sites under three respective categories of over all web brands, social networks&blogs and video brand.
Top 10 Web Brands in 2011
Google
Facebook
Yahoo!
MSN/WindowsLive/Bing
YouTube
Microsoft
AOL Media Network
Wikipedia
Apple
Ask Search Network
Top 10 Social Networks & Blogs
Facebook
Blogger
Twitter
WordPress
Myspace.com
LinkedIn
Tumblr
Google+
Yahoo! Pulse
Six Apart TypePad
Top 10 Online Destinations for Video
YouTube
VEVO
Facebook
Yahoo!
MSN/WindowsLive/Bing
AOL [...]