A spider web design for banners (This one's texture can easily be made using the cobweb's item texture stretched over the basic Banner shape) - Pattern created using cobweb and paper

A Spider Design for on banners (This one doesn't have to be too complicated, it can be as simple as a circle with 8 L shaped legs. It worked for Spiderman's classic design, so it should work for Minecraft just as easily! xD) - Pattern created using a spider eye and paper