Lucidity allows you to select a background image as a wallpaper creating a translucent effect for your entire desktop.

This just a fun way to have a favorite image set as an always-viewable desktop image. There are a few settings that you can use like transparency level and hotkeys but it is pretty straightforward desktop enhancement. It works by allowing most subsequent open windows, browser tabs, etc., show the desktop image behind adding a little customization to your workspace.