First coined by Jason Priem in 2010 in a tweet, altmetrics stands for "alternative metrics" and refers to using the Social Web to measure scholarly impact. Altmetrics include the number of views, discussions, saves, citations, and recommendations across many platforms, including Twitter, blogs, Mendeley, Scopus, and many others.

The Altmetric Bookmarklet enables you to get free article level metrics for any article with a DOI or any article in PubMed and arXiv. Article level metrics include mentions by bloggers, tweeters, Facebook users, Google+ users, news outlets, and others, as well as readers on Mendeley and CiteULike.

***Note: Altmetric scores now appear in Scopus when available. They also appear in some journals, including Nature.

"Impactstory is an open-source, web-based tool that helps researchers explore and share the diverse impacts of all their research products—from traditional ones like journal articles, to emerging products like blog posts, datasets, and software." --About Impactstory

***Note: Beginning September 15, 2014, Impactstory will cost $60/year or $10/month. 

You can find other related tools in this directory.