ViralSearch lets you search and navigate cascades of people passing content on social media and distinguish between things that are not just popular but also became viral in a sense that they are being passed from one person to the next over many generations.
ViralSearch does this by analyzing news, videos, and photos shared within Twitter. It looks to see how many shares there were throughout the user base, over time and over generations of users.
For example, in this screen shot, it shows a story Tim O’Reilly shared and then the shades of blue show the number of generations apart with 3,451 descendants.
Here is a video from Jake Hofman of Microsoft Research explaining how it works:
Note, this is not available as a public tool, it is currently a research product.