The Internet is a social and intellectually challenging place, but we don't need to tell you that. Here's an article that summarizes Social Research & the Internet (from Yale):
"The Internet has unique, even transformational qualities as a communication channel, including relative anonymity and the ability to easily link with others who have similar interests, values, and beliefs. Research has found that the relative anonymity aspect encourages self-expression, and the relative absence of physical and nonverbal interaction cues (e.g. attractiveness) facilitates the formation of relationships on other, deeper bases such as shared values and beliefs...Despite past media headlines to the contrary, the Internet does not make its users depressed or lonely, and it does not seem to be a threat to community life--quite the opposite, in fact."
There are always be naysayers, though, like here. But in even a large German study that concluded that math and reading suffered in households that had multiple computers, they also found that "academic performance rose among those who routinely engaged in writing e-mail or running educational software."
The Internet and Social Life