ImageKit.io - Instant multi-platform image optimization
CloudSight - Image recognition API; send an HTTP request with an image, get a description of contents.
Promo.com - Every promotion starts with Promo.com.
Dashmote - Dashmote bundles stock image providers to make finding stock images as easy as possible.
Promo Instant Image Resizer - Automatically optimize images for web & social media (free!)
Rubric - Generate an instant, cool caption for your photo