Zenity - Zenity is a tool that allows you to display GTK dialog boxes in commandline and shell scripts.
Flashlight - Control your Mac with a keystroke.
Glade - Glade is a RAD tool to enable quick & easy development of user interfaces for the GTK+ toolkit...
Tiny Flashlight + LED - Tiny Flashlight + LED is free to use application that can be used anywhere else, having nicely built-in functionality.
Yad - Yad (yet another dialog) is a fork of Zenity with many improvements, such as custom buttons...
MEEFF - MEEFF – Make Global Friends app allows users to learn the Korean language and increase their knowledge about Korean culture by making friends from Korea and engaging in live chat with them.