Paper clip radiators! I'm going to file this under 'appliances'. These colourful radiators become wall art, rather than "clunky ugly utilitarian heating system". And they take up very little depth on the walls.
Make a corner nook look bigger by placing a small desk in the center and then covering the surrounding area with art. Hang a small shelf on the wall for your office accessories, and complete the look with a plant and cool lamp.