The current system of measuring research impact, by traditional means like journal impact factors, may show how often a journal is cited, but says nothing about how its articles are really being used. Increasingly, researchers work in an environment driven by social media - many have blogs or websites while increasing numbers tweet about their research in an attempt to extend their readership. Scholars also use new networking tools like Zotero and Mendeley to share information.

For researchers who live and work in that kind of world, alternative metrics enable them to track how they're doing. This Chronicle piece, Scholars Seek Better Ways to Track Impact Online, looks at some of the tools and personalities in the 'altmetrics' universe. Jason Priem has written the altmetrics manifesto, and the web site Total-Impact provides tools to measure alternatives to traditional impact. The site includes a disclaimer though: "The meaning of these metrics are not yet well understood."

On Twitter, search for the #altmetrics hashtag.