The Huffington Post home page is a collage of content, articles are selected on news relevancy and popularity in the 4 hour news cycle of social media.
What's interesting about the Huffington Post home page and the way in which content from social media is highlighted is that instead of pushing that content is popular in social media, the content is highlighted first, and as an aside you learn the the content is popular in social media.
On the Post, top articles change constantly. The most popular content by pageviews, the most shares in social media and top comments by rate of growth are featured.
Several times on the Huffington Post home page what's hot on Twitter is highlighted with an individual section, featuring a headline, image and number of comments associated with the article.