Again...woah..
These are just.....awesome... I wouldn't be suprised if you got a job is an artist. Hmm... I wonder what your own sketches would look like. Once more, I bow down to you.
Wait a second.... you're self tought??? Woah........
Art classes would help if you wanted to make this a life time thing. Like Statikk said, you should take classes to control your talent.
Keep up the awesomeness.