Stackexchange is far more then finding things you cant Google. (By the way most question show up on google :) "Stack Exchange network has grown to include 153 different communities visited by over 105 million monthly unique visitors." Meaning in my point of view each community has unique users that are on it to help others answer questions they may have on their topic. You can find more on the tour page http://stackexchange.com/tour
Deep Web
This site is for question concerning the deep web (how to what it is and more)
And yes that can not be reached on traditional web servers.
Hope this help :-)