This is my response to
Martin's article: the picture on the left shows [[Mars_(planet)|Mars]] in a quite detailled picture. I'm just impressed by most pictures from space, be it planets, nebulas or galaxies: they all look fantastic and always make me think about who we are and what space is actually about, and how huge it actually is. That's why I have pictures from outer space on my desktops most of the time.
BTW: you can find a number of really nice space pictures on
hubblesite.org, with an own section dedicated to wallpapers.