You can create a background that changes colors when you change your theme’s color set. It’s really cool to watch. I’ve written about this before here, in an example that include a few objects on the slide. In this case, I wanted to show you a slightly different concept, which is a semi-transparent rectangle over a grayscale textured image.
You can find texture images by searching on photo websites. For example, here is Free Inages’s collection of abstract textures. You can also create your own textured images by photographing water, stone, tree bark, sand, etc.
Here’s what my textured background looks like.
Watch the video and then create your own textured backgrounds that can change color!