DrawAnywhere lets you sketch, annotate, and highlight directly on top of any screen. Great for following along video courses, recording tutorials or hosting presentations.

Highlights:

Stroke eraser toggleable via stylus buttons
Touch passthrough to the app below
50-step undo/redo operations
Minimal storage usage
Tips:

Long press and drag to move the toolbar around.
After 3 seconds of inactivity, the toolbar becomes more transparent.
Turn on Clear on hiding canvas to let the app clear the canv