Pewdiebot - Chat with the bot version of the king of YouTube, PewDiePie
CloudSight - Image recognition API; send an HTTP request with an image, get a description of contents.
SerenaBot - A simple chatbot for Serena Williams
YOLO - Real-time object detection
Kanye Cube Blast - Help Kanye beat the haters by basting all the cubes!
Rubric - Generate an instant, cool caption for your photo