Everyone already said what I wanted to say, so I just want to post for the sake of heaping more praise on you
I love your shading technique. The characters really seem to pop out of the page, particularly against the dark background.
I also like that you use several different techniques for different pictures, like the cel-like shading for the Invader Zim picture versus the chalk pastel look on the Daft Punk picture. What kind of tablet do you use?