As a comic artist and a student, I have devoted quite a lot of my time writing comics on the subjects that I study for my benefit and the benefit of my friends. They'll soon all be up here for you to download... some for free and some of the larger ones available as pdf e-books for a small price. I write study aids on all 'parrot' subjects, i.e. subjects that require facts, like maths and chemistry, and not creativity, like the arts. English is borderline, so I do stuff for that. Ranging from GCSE to AS (and probably A2 soon once I start the course).