Social Crawlytics is a free tool that analyses URLs to establish how popular they have proved across the social sharing platforms.
It helps identify which pages are the source of your best share count per social network. It shows how many shares you have received by content type, useful for figuring out which medium your shares come from. The content types are taken as reported by the server handling the content.
All you need is a Twitter account to sign up for a scan, so why not give it a go!