Portable notepad

I think this guy needs to invest in a whiteboard or something.

XKCD

For fans of the comics see if you can work out what panels they're from.

I'll start off easy

yay for graph jokes

"I'm not very good at this":

Even I have no idea what this is from (but google found it for me =] )

and a slightly easier one

Links to the comic strips after the jump