Looking at cookie cutter shapes gave me a good idea. Yes the very popular gingerbread boy would make an excellent shape for CNC cutting. There are several variants in the file, so you can choose your favorite. The individual files are also small, less than 500 lines of Gcode, so you can even use the boys to test drive the demonstration version of Mach3. Download the the gingerbread boy super pack and have fun.
I found a set of rather intricate butterfly designs on the web. I particularly like the detail found in how the wings were drawn. As an added bonus the designs did not need to be reworked for cutting by a two dimensional machine. I cut one of the butterflies, scaling to around 5 inches, and it looks great.