CloudSight - Image recognition API; send an HTTP request with an image, get a description of contents.
SerenaBot - A simple chatbot for Serena Williams
Dashmote - Dashmote bundles stock image providers to make finding stock images as easy as possible.
Kanye Cube Blast - Help Kanye beat the haters by basting all the cubes!
YOLO - Real-time object detection
Pewdiebot - Chat with the bot version of the king of YouTube, PewDiePie