Hitachi-powered image search site GazoPa (boy, they're really out of web names, no?) is a fairly robust engine for finding same or similar images. Its differentiation comes in hunting similar videos, digging through Flickr and letting you draw your search.
Yep, you can use GazoPa's simple drawing tool to roughly outline the type of image you're looking for, and GazoPa will use its search prowess to find, well, something akin to what you scribbled. As you can see from the test result below, it knows the basic shapes and colour tones you're going for, but we don't have to worry about CyberNet overtaking collective human intelligence just yet.
For images you're passing on a URL or upload for, GazoPa seems a lot more serious and useful. Hover over an image to get a good deal of info, or to perform another similar search for that picture. The Flickr integration is very useful, allowing for Creative Commons licensing filters, and video search worked for a quick Google demonstration frame I uploaded.
GazoPa is free to use, no sign-up required.