Draw Something (like Pictionary) is in a sweet spot. To begin with it's a game and people play with their friends. They leverage Facebook to find your friends that have the app already. You can still invite people that don't have it yet, but knowing someone already has the app makes it a lot easier to start a game.

They limited some features so they can charge for them. You only get a few colors but can buy more. You get "bombs" that act as hints and can buy more.

One thing they don't do yet is have a way to share your drawing (or animated replay) on Facebook. That would be a big help. I read about a "paint for cats" iPad app (I think the one below) that added a "Share this painting on Facebook" button and it blew up his traffic. Not sure it really applies to illico but it could to a more visual app. http://itunes.apple.com/us/app/paint-for-cats/id427702410?mt...