Y PPA Manager - Y PPA Manager is a GUI tool to add, remove, purge, list and search for Launchpad PPAs.
Chocolatey - The sane way to manage software on Windows.
add-apt-key - This command line tool can be used to add a GPG key to your APT key ring.
Scoop - A command-line installer for Windows
Introduce PPA - The program saves you from having to open the console to add a new PPA.
Ninite - Ninite is the easiest way to install software.