Following my Rainmeter blog post that was for Windows Only, this is the alternative for rainmeter but for Mac,
Geektool is a "mac" based desktop customisation tool, with various open source script and log capabilities that allow you to tweak and change what is displayed on the startup desktop. Such as text, text font, bar colour, time. This is the same as it's windows alter ego; Rainmeter. However Geektool allows specific alterations to mac only just as rainmeter allows you to tailor themes in Windows only.
Video on How to set it up: