making banners is something I often do with the photos I take, and sometimes with photos I find. But I can't put a line of text on the banner giving credit to the source, and rarely do I feel the desire. I usually simply don't care if you know where the image comes from that I use as a banner.
But i just found a great source of 1920's images and want to keep on Kat B's good side, http://fuckyeah1920s.tumblr.com/ is one of her websites. http://10110101.tumblr.com/ another that is just Los Angeles in the 1920's and 30's