I was very happy when I finally got my ThinkPad X200 Tablet, which is a Convertible, with a screen which is also a graphic tablet. It rapidly reduced the amount of paper I used, since I can do the usual scribbling directly on the screen. Under Windows, there is a nice software, called Windows Journal.
A similar software which is platform independent, and which I like more meanwhile, is Xournal
. It is my preferred tool for taking quick notes or just scribbling around. It has functionality for "rubber and pen", and lined paper, so it is quite easy to work with.
And it is my preferred tool for annotating PDF files, even though these files sometimes appear wrong on Apple-software (I still do not have any clue why).
It is also good for drawing images which should look like "natural drawing".
I like this software, and I use it very often. Meanwhile it definitely belongs to the software I install by default whenever I begin to use a new system.