Thought that space-loving Dopers might be interested in this.
The folks at the Jet Propulsion Laboratory have produced a series of 14 posters, done in a style similar to the great old WPA posters of the 1930s, that imagine what advertising posters for travel to other planets might look like.
Each poster is available as a free, high-resolution download (about 40-50MB per poster) suitable for a 20x30-inch poster. You can also download the whole collection in a single 641MB file.