"This tool comes with a warning in that it may take quite a while to run on large models. In order to accurately and reliably get the groups that truly are visible in a view, it must open and activate it prior to querying the groups. The result is a CSV file listing each group along with their ElementId with the group name, group kind, and view name."
Update 5/8/2016: CASE and the CASE Apps website are no more but, courtesy of WeWork, the CASE Apps are now open source. They may be accessed on GitHub.
Further reading: Free add-ins.