add-apt-key - This command line tool can be used to add a GPG key to your APT key ring.
Beyond Compare - Beyond Compare allows you to compare files and folders.
launchpad-getkeys - Launchpad-Getkeys is a script (comes packaged in a .
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
Introduce PPA - The program saves you from having to open the console to add a new PPA.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.