Using Gimp or a similar program, create a public service announcement billboard on something that really aggravates you about people, society, the world, etc. It can be serious, goofy, but not offensive. Use a 680 x 300 work space in order to mimic the space of a billboard and have fun with how your positioning, font, colors, and images can help get your message across in a small space. Take it to the next level but superimposing it on a photo of an existing billboard!