Awesome-Selfhosted
If you are not familiar with awesome-selfhosted, it's a large and every growing list of free web applications and network services that can be self hosted.
I recently noticed that they now have a website with a search feature, which is way easier to navigate than their GitHub page. Not only that, but TheRealM0e over on Reddit recently created their own website that pulls from the official GitHub and plans on adding other lists like Awesome Sysadmin in the future.
If you aren't sure where to start or just want to see what other popular applications are out there then these websites are a great place to start.
https://awesome-selfhosted.net/
https://github.com/awesome-foss/awesome-sysadmin
https://github.com/awesome-foss/awesome-sysadmin
Other useful sites