gInk - An on-screen on-screen annotation software for Windows.
Epic Pen - A windows tool for drawing over your desktop and applications
Ardesia - Ardesia is an usefull software for use your desktop as a Sketchpad.
ScreenMarker - ScreenMarker is a lightweight tool that lets you write and draw on the screen.
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.