One of the most useful tools for creating digital line art (i.e. comics!) is the geometric edge tool in Poser 11. It's called the Live Comic Book Preview, and it offers the most versatility of any of the commercial-grade 3D tools that I have tried so far.
Just so I don't lose track of it, here's a useful tutorial on how it works.
Generally, I don't agree with what he says about lighting, but that's just because he's working in limited color and I work in black & white.