Ive noticed you have a few tutorials planned and there are a few which look good including, shopping cart and how to use ajax, i am ok at php and learning oop at moment but i am a major novice at ajax so that will be good.
Anyway i think one for using the facebook api would be good.
How to login using it, how to get information back from it etc.
Facebook API
Re: Facebook API
Probably not something I will do any time soon, their documentation is pretty good though