Speedy Painter is an OpenGL based painting software for Windows. It supports Wacom digitizers to vary size and opacity of brush strokes according to pen pressure.
Intro

Features:

Reference view that follows zoom! Available using the F3 key

Export drawing process into a video: ready to upload it on YouTube!

Multiple layers

Ability to vary stroke size and/or opacity according to pen pressure (supports Wacom digitizers)

Replay of drawing process

Import/export drawing process

Loading of most common image formats

Canvas rotation

Canvas flip

Selection mask