Many times when answering I put some image that I found googling.
As I understand it, this requires citing the source where the image comes from. Since this is specified in the policy, wouldn't it be a nice feature to create an automatic reference to the original image when said image is embedded?
Examples (borrowed from the answer and comments):
Image description
Tooltip (see markdown for difference)
Superscript caption
Courtesy of creativecommons.org