This free bookmarklet from Altmetric lets you instantly retrieve altmetrics data for most articles*:
Available for Chrome, Firefox, and Safari.
*Caveats from the altmetric.it page to keep in mind:
Examples of altmetric activity:
This page of the Altmetrics for Researchers LibGuide from Duke University has excellent examples of incorporating altmetrics into the above applications.
5 tips for interpreting your altmetrics data---Essential strategies for building upon your altmetrics data, by Cat Chimes of Altmetric.