If like myself you like your desktop wallpaper changed often with cool stuff, you might find this site useful: http://antwrp.gsfc.nasa.gov/apod/astropix.html. Every day there is a new picture related to astronomy posted and you can download them in high quality as well. Some of them are indeed artists impressions of various events yet to come, but most of them are actually pictures taken by the likes of Hubble Telescope or various other space missions. So it’s worth visiting every day — if not for the information offered (below the picture), at least for the picture itself.
Also, check out the Archive area and harvest for more pictures there. One of my favourites (probably because the New Horizons mission is getting closer to Jupiter) is this one http://antwrp.gsfc.nasa.gov/apod/ap060725.html which gives you a look at Jupiter’s 2 largest storms.