I did just read on Huffington Post about a dating website which has "virtual dating" -- code in which you upload a photo of yourself and it makes you an avatar, which can then talk and have drinks and dinner with another online person who has done the same thing.
The site is Omnidate and they call it their "Photofit" feature. This sounds pretty much exactly like what the OP is asking for. Upload a photo, get an online avatar based on that photo.
Just put Vulcan ears on'im and you're good to go, Captain!
I can draw a cartoon with Angelina Jolie in it, publish it in a newspaper, and it's not illegal.
I can draw a picture of Angelina Jolie and sell it on the internet or on a streetcorner. That's not illegal either.
I can take a picture of Angelina Jolie and sell it to anyone I want. That's not illegal either.
Actually that is not true... You are not allowed to use someone's likeness in the pursuit of profit. Same goes for taking pictures with people in them. Technically, if I got to the beach and take a beach photo and there happen to be people in it, I have to get them to sign a waiver if their faces appear anywhere in the photo.
As for using someone in a newspaper comic, that is sometimes covered under the satire provision of US copyright law, but one has to be very careful that it is properly satirical.
Another example would be any case involving Albert Einstein's likeness. Upon his death, his likeness was given to Hebrew University. In fact GM was just sued for using his image in a magazine ad without getting the proper permission.