ImageJ - and Other Health Care
Epic Pen - A windows tool for drawing over your desktop and applications
Avogadro - Avogadro is a free, fantastically easy to use molecule editor.
gInk - An on-screen on-screen annotation software for Windows.
ACD/ChemSketch - ACD/ChemSketch for personal and academic use brings the power of our structure drawing package to your home computer.
FrontSketch - Highlight, annotate, draw, capture, write on your computer screen during run-time