Epic Pen - A windows tool for drawing over your desktop and applications
gInk - An on-screen on-screen annotation software for Windows.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
FrontSketch - Highlight, annotate, draw, capture, write on your computer screen during run-time
Pylote - To draw on the screen and to handle the instruments of geometry there.
Gromit-MPX - Create annotations by directly drawing on your screen.