Blender is a free software. now you can paint in 3D with textures and images.
http://www.blender.org/

here is a free tutorial that shows you how you can texture your model. if you want you can use this tutorial to make a tatoo on the body. why this tutorial? because the software is free and because you can do it over seams. we know that seams a a big problem when it comes to texturing.
www.blendercookie.com/2009/06/18/texturing-with-projection-painting/