Like most internet users, you probably grab images from a basic Google image search. Well, thank your lucky stars that there are some nice alternatives to just "googling" for medical images.
Check out the Radiology Picture of the Day blog. A new image is posted daily that is provided by a physician with a brief description below about the image with related references.
The blog is edited and maintained by Dr. Laughlin Dawes, a diagnostic neuroradiology fellow at the Sir Charles Gairdner Hospital in Perth, Western Australia. The images date back from November 2006 to the present.
I prefer to navigate this blog via its ARCHIVE page that categorizes the images for you. There is a link to suggest an image that you would like to submit to this blog, as well.
As always, give credit where it's due if you are going to use any image from the web. For example, if I were to use this image
I would reference this image as:
Congenital cystic adenomatoid malformation. Image provided by Dr. Ahmed Haroun. Posted Feb 28, 2008 on the Radiology Picture of the Day blog. Accessed on June 30, 2008 at http://www.radpod.org/2008/02/28/congenital-cystic-adenomatoid-malformation.