Zemanta is an online platform for finding and adding “relevant images, smart links, keywords and text” to blog postings. Available in numerous incarnations (Firefox add-on, WordPress Plugin, etc.), Zemanta queries the text of a blog post against their own “proprietary natural language processing and semantic algorithms” to formulate media recommendations.
Images are pooled from Wikimedia Commons, Flickr and various stock photo providers – as a result, a large number of the photos are CC-licensed. The Zemanta interface displays what license a photo is released under before it is added to the post, making it clear to bloggers what permissions are allowed. You can read more about what Zemanta does here – it is a simple and efficient way to add rich media to blog posts and best of all, its free.