For me, Wacom tablets or tablet-with-stylus kinds of devices. Now it's not only a whiteboard, but I can take screenshots, collaborate with countless others, un

For me, Wacom tablets or tablet-with-stylus kinds of devices. Now it's not only a whiteboard, but I can take screenshots, collaborate with countless others, undo, search, zoom and pan infinitely, etc... And they can be had for around $100 or less.