If you're looking for some retro-inspired brush work sketches, check out the work of Toronto cartoonist Michael Cho. He throws down some serious two tone gouache and ink works with some really well planned out interplay between light and darks. His style looks great with comic book characters and action heroes, and also brings to mind illustrations for paperback novels in the 50's. His best work includes more detailed renderings of Toronto's back alleys, to be published as a collection in an upcoming book from D+Q later this year.