The static map API discusses paths, but no mention of circles. Is this possible? Thanks
What you could do is use the encoded polyline algorithm to produce enough points to get a roughly circular path. There's definitely coding involved: you'd need to get the center and radius of your circle, turn that into a series of lat/longs, then encode using the algorithm.
As an alternative, you might be able to use a transparent gif image as a marker and put that in your map.