tmux-applets is a collection of tmux "applets" that are designed to be used in tmux's status bar. They are non-textual, using blocks of color instead. Currently, there are two applets provided. tmux-cpu-freq displays the CPU frequency level as colored blocks, and tmux-ping, which tries to ping a host and displays success or failure as a colored block.
Compa is a GNOME panel applet which can display the output of any system command on the panel. It can also display the output of a different command in its tooltip, and launch a different command when clicked. The text style can be modified using the Text Attribute Markup Language.