This is Messier 51 taken using the MicroObservatory and processed using AstroImageJ and GIMP. This image is made up of a stack based on 16 observations.
I discuss both the MicroObservatory and AstroImageJ in my book.
I processed this image in AstroImageJ by first importing the sequence of 16 images and then aligned as I described in the book.
I adjusted the scale to bring out the details of the galaxy and also lightened the background. In GIMP, I used a Curves adjustment as described in the book to darken the background and maintain the brightness of the galaxy.
You can see that this image is a little out of focus but the result is still quite good considering this was taken over the course of a month in various weather conditions and taken using a completely free service. Compare this image to the image from Slooh.com and processed using MaxIM DL.