I was browsing the web this evening and came across an awesome image of a galaxy called the Sombrero Galaxy on the Hubble website. While the picture itself is pretty neat, the detail you can see in the background of the highest quality image.

If you download the full-size image (approx 7 MB) and look in the darker areas around the edges, you can see small galaxies in the background of the image. It's crazy to see how many other galaxies are in the background of this one shot. Check out the high-resolution version to see what I mean.