One of my favorite things about Github is that there are repositories that collects and curates a list of awesome things for a specific topic and everyone can submit a pull request and add their own awesome things to the list. Awesome-Selfhosted (a list of things that you can host on your own server) and Awesome Sysadmin (Curated list of sysadmin resources) are some of them, but this new list is also great: Awesome Linux Software. Check it out.