I figured that if I'm going to be staring at my printer while leveling the bed, it might at least be interesting.
This should be printed without any build plate adhesion, and infill and support doesn't matter.
I've included a basic file that just has four squares in the corner -- don't try the mario print until these four squares lay down well.
Mario is designed to be pretty tough -- the picture is split into separated pieces to force a bunch of retractions and starts. If you can run this at full speed and successfully stick all of the first layer, you've got a level bed.
The second layer is put down to make it easier to remove the print from the bed. If you really want, scale it in the Z direction to put down more plastic and make it easier to remove. Without scaling you should get two layers if printing at 0.175 mm per layer.
The stl about 100mm square, sized for the Monoprice Select Mini, which has a 120mm square bed. If your bed is larger, just scale it in the x and y direction appropriately.
I printed with Cura default PLA settings, except for removing build plate adhesion.
This was produced by manipulating the picture in Gimp editing software (dilate filter to thin lines), converting bmp to svg with potrace, and then feeding that into http://svg2stl.com. Finally I scaled and layered the stl with openscad.