The super cool Santa Cruz Artists over at Local Santa Cruz gave away a free beach wallpaper download today. You should go check it out and decorate all of your devices!
Download it from their site: Beach Wallpaper
Local Santa Cruz has done one of these before too; a Victorian Wallpaper, that shows the Walton Lighthouse at the harbor. Their Victorian wallpaper is linked to from the icon wallpaper too if you want to take a look.