Slammer

Slammer... The Designer's Geometry Box 8 way resizable sculpted frame and ruler Customizable Themes Flexible origins Layers can be used to section the canvas Overlays add grids within the layers Uniform(Typographical grid), Fibonacci Section Golden Section & Harmonious (equal) distributions Screenshots with or without the grid Clickthrough mode for interacting with the objects below.

Magnifier, Crosshair and color picker Global Hot Key to toggle the Slammer Window from anywhere
Watch the movie: http://ringce.com/slammer/movie