Annie Sloan's Frottage: Paint one coat of the first shade, then while the second coat of the next colour is wet, take sheets of crinkled newspaper and rub it all over and then pull it off. The paper pulls off some of the paint revealing the first layer.
DIY: Tuscan Faux Paint Technique - easy tutorial on applying this great paint technique to your walls. -- This is for my crazy idea of making a tiny house out of a grain silo. This technique would be perfect on the concrete block interior.