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:
- The Bookmarklet only works on PubMed, arXiv or pages containing a DOI
- It only supports publishers who embed Google Scholar friendly citation metadata on their pages by default, though we're adding support for others. You can hurry along support for a particular journal by asking @altmetric for it on Twitter
- Twitter mentions are only available for articles published since July 2011
- If Altmetric started supporting a publisher after July 2011 then Twitter mentions are only available from that date onwards