There really is nothing like comics to tax the limits of drawing and imagination.
On the tools aspect, I'm a fan of Microns and the Pentel Pocket Brush Pen, although I do tend to work digitally a lot more nowadays. I've been thinking about gravitating back to bristol board and ink though... there's nothing quite like a physically finished page. I imagine I'd still do layouts and rough drawing digitally, that's where the ability to undo, play around, and transform are immensely useful.
I'd love to work digitally some day, too. But for now I'll stick to my Le Pen Technicals ;)