rflickr is a Ruby implementation of the Flickr API. It includes a faithful reproduction of the published API as well as method encapsulation to provide more useful object mappings. rflickr features result caching to improve performance.
You are a major brand wanting to advertise. Do you: A) hire an advertising agency and pay big bucks for photo shoots, or B) crowdsource images from your fan base for free? The Olapic API integrates answer B into other apps.