I draw self portraits in MS Paint, and I like to post the ones that I find to be the most well done and the closest to my actual likeness up as my profile pic.

It helps you all to know exactly who it is that you're talking to without actually giving the stalkers and freaks a picture of myself (blatantly)

Naturally, I assume that all you cartoony folks have your actual selves in the profile pic.

Or, at the very least, it's a pic of who you wish you were.

Or, at the absolute least of that, it's a depiction of how your avatar feels it should present itself to the world.