When digital imagery in astronomy came along about 25 years ago, I knew right away it would change everything, but one thing I didn't expect was the advent of citizen science. Spacecraft and observatories store their images on hard drives, and anyone with access and the knowledge of how to process that data -- no simple task, I assure you! -- can use it to do their own work.
It also means smart, talented people can take that data and put it together to make stunning pictures of space that otherwise may never see the light of day. Gordan Ugarkovic is one of these people. He's a Croatian software developer, but in his spare time takes data from spacecraft and makes simply devastating portraits from them. Like this one of Saturn's moons Tethys and Titan as seen by Cassini:
[Click to enchronosenate.]
Anyway, the detail is stunning in his original high-res version. You can see craters on Tethys, and the thick atmosphere enshrouding Titan (including the north polar haze cap). The image is very close to natural color, so this is approximately what you would see if you were there (shortly before freezing and asphyxiating, but what a way to go).
Gordan has done many, many such images, including this moody shot of Titan and Rhea, and this simply incredible wide-angle shot of Titan and background stars shown inset here (click it to embiggen, and trust me, it's awesome).
Wanna give this a try? Raw Cassini images are stored online, but it's not as simple as you might think. Still, you might have fun, and Emily Lakdawalla from The Planetary Society Blog (who does this herself as well) pointed out to me that this Web interface has raw data from Cassini, Galileo, and Voyager, and more missions other missions are online too.
In general, there are so many images from these spacecraft that the scientists on the teams themselves don't have time to look them all over. It's entirely possible you'll find something new and interesting. If you do, make sure you check out the Unmanned Spaceflight forum, which has loads of space enthusiasts who spend a lot of time working on this stuff. I go there fairly often to see what's new, and you should too.
Image credit: NASA/JPL/Space Science Institute/Gordan Ugarkovic (used with his permission)
* The first person to leave a comment saying "That's no moon" will get a light saber up their Tauntaun.