The stock photo site Unsplash recently launched APIs that grant users access to the site's entire library of over 30,000 high quality images. The API comes in two flavors: Unsplash Source and an entire JSON API. Unsplash launched a few years ago as a basic Tumblr blog.
The Aviary Effects API that helps developers create their own Instagram recently made the API public and updated its developer portal. In addition, the company is offering a short-term developer contest, so you'll need to get going quickly.