There may not be many posts on this blog but one of the most popular has always been “Desktop clock with geektool” (possibly because Google directs people here looking for actual physical desktop clocks, but still).
The release of Geektool 3rc4 brings change. It’s a much slicker design, with the ability to export “geeklets”, allowing easy exchange of any commands. So attached below is my desktop clock as a geeklet, which you can import and modify to your preference.
This is what it looks like on my current desktop:
Download the Geeklet.