The Unsplash API - No-limits, do-what-you-want API for access to 200K+ HD pics.
New Tab by Flickr - Get a beautiful photo each time you open a new tab
Amazon Rekognition - Add Amazon's advanced image analysis to your applications.
Minimo - An elegant, simplified new tab page
PublicAPIs - Explore the largest API directory in the galaxy
Tabpin - A browser extension for people who use lots of pinned tabs.