Altmetrics measure impact in a different way. They take into account the rise of social media in the raising of research profiles through the analysis of activity in online tools and environments. As such they can be helpful in discovering where research has affected policy or been discussed in the media.
Altmetric.com is a company who provide a free tool for gathering altmetrics on specific papers at http://www.altmetric.com/researchers.php. They also have a guide to altmetrics at http://www.whatarealtmetrics.com/.
Cinahl Complete features information on social media mentions for some articles. Where this information is available, the Plum Print icon will show and you can click on this to get further details. The Plum Metrics are created by Ebsco.
For some articles in Scopus, you will see additional citation information which includes scholarly and social activity gathered from social media routes - this appears when you display the full reference for the article you are interested in and you can then follow a link to more detailed breakdown of the mentions.