Find Journal Information & Scholarly Metrics: Google Scholar: Metrics and Self-Citation Counts

Google Scholar Metrics lists the top journals by disciplines and subdiscilplines based on the journals' five year h-index and h-median.  The methodology behind h-index calculations is explained on the Google Metrics website.

You can also use Google Scholar to track your citations. 
"Your citation metrics are computed and updated automatically as Google Scholar finds new citations to your work on the web".