> Any tips on how one can create xkcd-style graphs? Where things look hand-drawn and imprecise.

Umm, draw them by hand? I don't want to seem to be stating the obvious, but ...

Options:

* Take some fine-point felt pens, draw the chart on paper, and scan it.

* Use a drawing program that has a freehand option, a mode where you can sketch using a mouse or other pointing device.

* Take an art course, fail the course, but succeed in getting the requisite materials.