Synaptic is a graphical package management program for apt. It provides the same features as the apt-get command line utility with a GUI front-end based on Gtk+.
CopyQ is advanced clipboard manager with searchable and editable history with support for image formats, command line control and more. Command interface and graphical interface accessible from tray. By default the application stores any new clipboard content in list in the first tab.
Nuvola Player runs web interface of cloud music service in its own window and provides integration with a Linux desktop (system tray, Ubuntu sound menu, dock menu and notifications). Currently supported services are Google Play, Grooveshark, Hype Machine, 8tracks and other.
Kazam is a simple screen recording program that will capture the content of your screen and record a video file that can be played by any video player that supports VP8/Mp4/WebM video format. It also records audio from any sound input device that is supported and visible by Pulse-audio.