Tattoos come in some fantastic patterns especial the tribal and celtic ones and you can find hundreds of designs in Google images.
As well as having them on your skin wouldn't they make great templates for doodling? When you are stuck and fed up with doodling the same thing, they could be a great source of inspiration.
You could draw them free hand on to your LOs or they would make fantastic overlays by tracing them on to acetate with a permanent marker or putting the image into a word doc and printing on to acetate. I'm definitely going to use this idea for a mini album I'm going to start in the next few weeks. If you have already tried it or you have ago after reading this then I would love to see it.