ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Limnu - Sketch, share and collaborate with your team
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Sketchboard.io - Visual Remote Teamwork. Solve problems and create ideas on endless whiteboard with your teammates by sketching.
LightShot - The fastest way to take a customizable screenshot.
MultiDraw - Draw with others in real time.