You can track Altmetric.com scores for various articles and other items by signing up for their free browser extension tool, the Bookmarklet.
Altmetrics aim to measure the impact of scholarly activities outside of traditional academic publishing and citation counts. Scholarly communication is increasingly occurring in the online environment--in social media via blogs, Twitter, and sites such as Mendeley--and traditional scholarly metrics cannot capture the impact of discourse in these venues. There is debate about whether altmetrics should complement or replace traditional metrics.
There are a number of new tools and websites that are trying different ways to measure impact in the online sphere, aiming to assess impact through how much a work is discussed or read, rather than just how much it is cited in scholarly journals.
Reveals impact of anything with a digital object identifier (DOI). Full version requires subscription, but Altmetric It is a free bookmarklet for Chrome, Firefox, and Safari. Currently only works on YouTube, arXiv or pages with a DOI; publishers must embed Google Scholar friendly citation metadata.
Requires subscription; target audience is institutional subscribers.
"Plum Analytics tracks more than 20 different types of artifacts, including journal articles, books, videos, presentations, conference proceedings, datasets, source code, cases, and more."
Altmetrics.org: Manifesto on altmetrics, as well as links to news, tools, resources, and events about altmetrics.
What Are Altmetrics - Produced by Altmetrics.
Jason Priem's Website: Website of Jason Priem, one of the founders of Impact Story and a strong proponent of altmetrics. Writes on many topics related to altmetrics, including the open data movement, changes in scholarly communication, and author rights.
The Scholarly Kitchen: Moderated blog on "what's hot and cooking in scholarly publishing." Many posts touch on issues related to the impact of publishing and how scholarly communication is changing. See Celebrating Five Years of Altmetrics by Charlie Rapple (from Oct. 2015) for a summary of recent developments in the altmetrics arena, or Altmetrics -- Replacing the Impact Factor is Not the Only Point (from Nov. 2012) for a good overview of issues related to altmetrics.
Article by Heather Piwowar: "Altmetrics: Value all Research Products," Nature 493.6431 (2013): 159. In discussing the NSF decision to ask for research "products" rather than publications, the author calls on scientists to "build and use tools and infrastructure that support open dissemination of actionable, accessible and auditable metrics."