Being a GNOME Shell extension itself, Argos adds a button with a dropdown on the GNOME Shell top panel. This button can display or expose functionality provided by a script, be it Bash, Python, Ruby, and so on (remember to make it executable or else Argos won't use it).

I recently stumbled upon an interesting tiny old script which can translate any text you select. After highlighting the text, be it in a web browser, Libreoffice or PDF document and so on, upon using a keyboard shortcut, its translation is displayed in a desktop notification.

Liquid Prompt is an adaptive, smart prompt for Bash and Zsh. It can display various useful information on the shell prompt, only when it's needed, like the battery status when it's discharging over a given threshold, an up arrow if using an HTTP proxy, the number of detached sessions  (screen or tmux) and more.

Indicator-Sysmonitor (System Monitor Indicator) is a really interesting Ubuntu indicator because it allows you to display pretty much anything on the Unity (or GNOME) panel by using a simple command or a bash script.

Currently there is no AppIndicator to display the actual network usage as in the actual values on the Unity panel in Ubuntu. We have Indicator Multiload but it only displays a graph so I wrote a script for Indicator-Sysmonitor to display the network upload/download speed as well as CPU and Memory usage (Indicator Sysmonitor already has CPU and Memory usage but if you want to use a script, you must get your script to display the CPU and Memory usage independently).