While doing research for an article, I stumbled upon a one-stop-shop for Ubuntu repositories. Quite a find, a website that has an “Ubuntu Sources List Generator” (You can find the website HERE). Basically, in the first two drop-down boxes, “click” your country, and your Ubuntu operating system (Precise, Trusty, Wily, or Xenial). Next, from an extensive list, “click” the repositories you want. Finally, at the very bottom of the page, “click” the “Generate” button. After a couple of seconds, you will see a new Sources List loaded with you new repositories. This list is complete with install instructions and GPG keys.
Here are some screenshots:
