The gzip Recovery Toolkit attempts to automate the recovery of data from corrupted gzip files (including tarballs) through a program called gzrecover. This package is still very experimental at this point.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.