The cairo-clock from MackSlow is indeed has very good look and feel. But it’s transparent background is depend on cairo’s alpha channel and Xorg’s composite extension. I did not enable this extension defautly because gnome doesn’t have it’s own composite manager and rely on xcompmgr. But xcompmgr always cause gnome-panel to be overlayed by other window. Then I think, “this clock almost won’t move after it was lauched, why not make a fake transparent background for it?” So that’s it, the screenshot: