Tyler Cowen calls this paper on ideological segregation online "one of the best papers on on-line media." Cowen highlights this tidbit:
A consumer who got news exclusively from nytimes.com would have a more liberal news diet than 95 percent of Internet news users, and a consumer who got news exclusively from foxnews.com would have a more conservative news diet than 99 percent of Internet news users....Visitors of extreme conservative sites such as rushlimbaugh.com and glennbeck.com are more likely than a typical online news reader to have visited nytimes.com.
Another paragraph:
The Internet makes it easy to consume news from multiple sources. Of course many people do get news from only one source, but these tend to be light users, and their sole source tends to be one of the large relatively centrist outlets. Most of the people who visit sites like drudgereport.com or huf?ngtonpost.com, by contrast, are heavy Internet users, likely with a strong interest in politics. Although their political views are relatively extreme, they also tend to consume more of everything, including centrist sites and occasionally sites with con?icting ideology. Their omnivorousness outweighs their ideological extremity, preventing their overall news diet from becoming too skewed.