Nicely done image editing and drawing application features non-destructive editing, multiple layers, live filters, and vector drawing tools all in the same window.

DrawIt includes a large number of ready-to-use and easily customizable special shapes; circles, stars, rounded rectangles and polygons, as well as support for an unlimited number of nested groups, masks and custom overlays. Supports over 100, stackable, nondestructive Core Image filters. Individual properties can be freely edited, regardless how many filters have been applied.

9WR - DrawIt: Bitmap editing, vector drawing tools, multiple layers, filters, masks.