Generate text banners in your terminal.
sudo apt-get install figlet
mdless - a Markdown viewer for the terminal.
quickchart.io - a server-side rendering library for Google Charts.
If you want to logout from your Linux desktop session, but don't want to leave your terminal window.
gnome-session-quit
From time to time I clean up all the local branches that have assembled over time in a Git repository.
git branch | grep -v "master" | xargs git branch -D