Over on the Radio Antics blog fellow RTL-SDR enthusiast Andrew has been using the RTL-SDR to receive Slow Scan Television (SSTV) amateur signals. SSTV is a method ham radio enthusiasts use to send small images to one another. The images often contain their ham call sign overlaid on the image.
Andrew was able to receive several SSTV images using an R820T dongle tuned to the 27 MHz (11 meter) band. He also used a Funcube Dongle+ and got similar results.
Check out his post for some of the images he received, and his video below for an example of the receiving process.