Actually, on reading, it’s a Windows app, too, so all of you can use it

I’m not usually a fan of the pointless graphical doodads, but this one is pretty nice; It displays a live-updating view of the earth as your desktop, with accurate sun- and moon-light mappings, and (given an internet connection) up-to-date cloud cover.

Pretty slick.

I don’t know how long I’ll be using my copy, but since I got it for free (and legally, too!) it might last for a bit.