Find out how many social shares a URL has?
sharetally.co
sharetally.co
Services like Sharetally are neat because they do the crawling for you, but the numbers still may not be entire accurate; especially if you consider URL shorteners and how various services crawl and report those. Even more confusing is why some services (in particular, g+) seem to over-report the number of shares, only to self-correct later on (by as many as 10-11).
I've been doing this stuff for a bit on my personal sites. Interested in how different networks contribute to link popularity.