Epic Pen - A windows tool for drawing over your desktop and applications
Helium - Helium lets you accept payments by credit card for anything you want to sell online.
gInk - An on-screen on-screen annotation software for Windows.
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
Gromit-MPX - Create annotations by directly drawing on your screen.
PiPifier - PiPifier is a macOS 10.