Creative Commons Finder 2014 is a tool which helps you locate Flickr pictures published under the Creative Commons Licence, which can then be republished and reused however you like.
The program is simple enough to operate. Just type in your search term - "Christmas", "Beach", "Tiger", whatever you need - and various matching thumbnails appear. Clicking any of these displays it in a larger view, and you can then download the picture, set it as your wallpaper, or visit its Flickr page with a click.
There are odd problems, though. It can take a while to download whatever photos the program has found, and that means several of the thumbnails may remain blank for quite some time.
The results aren't always what you'd expect, either. We searched for "New York" pictures which were freely usable without limitation, and although there were 494 hits, barely any gave us the city shots we were looking for. And yet, searching Flickr from the browser produced quality pictures immediately.
Perhaps we were unlucky; if you need to search Flickr outside of the browser then Creative Commons Finder 2014 might be helpful, at least sometimes. But for general use, we'd still prefer something like Google Images. It can also search for pictures which can freely be reused, even commercially, but will usually give you many more photos to choose from.