Free tools to assist in finding publication information:
H- Index: A measure of the impact of an researchers work, often the number and quality of citations.
G-Index: Alternative measure to H-Index, more credit given to highly cited papers.
i10-index: Used only in Google Scholar, counts number of publications with at least citations
Eigenfactor: Measures a journal's influence within the scientific community, based on number of citations from reputable journals.
Scimago Journal and Country Rank: Using citation data from Scopus, providing rankings by journal country of origin and numerous visual representations of journal impact data.
Google Scholar Metrics: Browsable list of the top 100 publications particular subject fields ranked using their 5-year h-index.
Altmetrics complement other citation based metrics by measuring the impact of work on social media and online reader behavior. Examples of altmetrics include Twitter, blogs, online downloads and facebook. University of California Berkeley has a great guide to altmetrics.