If your job requires you to know which topics are the most discussed on social media or if you are simply a curious denizen of the Internet, BuzzSumo will show you which links are making the rounds.
Head to the BuzzSumo Web site and enter a topic or domain name. BuzzSumo will return a list of articles that are the most shared across five social media networks: Facebook, Twitter, LinkedIn, Pinterest, and Google+. You can sort the results by an individual network or by an aggregate total shares.
On the left-hand panel, you can filter the results by article type and date. Below the filters is a Saved Searches section, where you can access any searches your curiosity or job requires you to monitor. You'll find a Save button in the upper-right corner to save such searches.
There are also advanced search options that let you search for exact phrases, search for multiple words, and exclude words from a search query.
For each search result, a Share button lets you share it on your own social network(s). Above it, the View Sharers button shows you who has retweeted a piece of content with various stats associated with each.
At the top of the page are two tabs: Top Content and Influencers. Top Content results are returned by default, and show you the most shared pieces of content around a particular topic or URL. Move over to the Influencers tab to see which Twitter users have the most traction on a topic or Web site. On the Influencers tab, you can filter by bloggers, influencers, companies, journalists, and regular people. You can also check a box to Ignore Broadcasters, which are Twitter users who are unlikely to reply to a Tweet and likely spammers or marketers.
BuzzSumo is free, but you get only a handful of searches per day unless you sign up for an account with an email address. Then, you can search all you'd like all day, every day. A paid BuzzSumo Pro service is in the works that will offer "exciting new features to provide even deeper content and influencer analysis."