ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Videogram - Auto create interactive thumbnails (GIF card) of video
Thum.io - A real-time website screenshot generator
PreFlight - Preflight is an Automated Web Testing tool. Allows everyone to automate Web UI tests.
Picmaker - Design the Future
The YouTube Thumbnail Game - Guess which YouTube video thumbnail has more views