With the TYPO3 extension code711_housekeeping you can keep an eye on your TYPO3 installations in the TYPO3 Dashboard. 

Projects are created as records and the data handler calls the TYPO3 API to get the latest version updates when saving. Either the project version is entered manually or the project's git repository is accessed via the GIT API and the installed TYPO3, PHP and extension version is scanned. A scheduler task is also available for frequent or bulk scans.

A TYPO3 Dashboard widget can be used to get a nice coloured overview of the status of the projects.