Do you use Flickr? They have recently come under fire for selling canvas prints and wall mounts of user-submitted photographs through their website without passing any of the profits on to the creator. Creative Commons (“CC”) licensing is allowing them to do this 100% legally.
There are a lot of different ways people use the service. I use it to store backups of photos. It also has a very robust “Advanced Search” feature, which comes in handy to find free stock photos.