For Unity: https://github.com/limpbrains/somebar

There's lots of these due to the plethora of minimalist tiling window managers demanding simple, scriptable info displays.

I use dzen2: https://github.com/robm/dzen

Xmobar is another popular one: http://projects.haskell.org/xmobar

This https://github.com/LemonBoy/bar and a few hundreds of its clone and frameworks.

I recommand getting the polybar clone by jaagr

https://github.com/jaagr/polybar

I have been using this one: https://extensions.gnome.org/extension/437/mylauncher/