I have a few that I have done over the years.

This is something I made for my graphics class and is my first time using an airbrush, you can see when I started (luffy's shirt) came out with very flat color but by the time I was done (luffy's pants) I was able to create a lot more depth.

This is a scratchboard I made of Zoro.

Something I sketched on the bus on the way home without a referance. I colored it as an experiment with photoshop. maybe one day I will redraw it better with a referance, and make Zoro's pants less green. ^^;