Letters should now be properly oriented:

CanvasRenderingContext2D.prototype.fillTextCircle = function(text,x,y,radius,startRotation){

   var numRadsPerLetter = 2*Math.PI / text.length;

   this.save();

   this.translate(x,y);

   this.rotate(startRotation);



   for(var i=0;i<text.length;i++){

      this.save();

      this.rotate(i*numRadsPerLetter);



      this.fillText(text[i],0,-radius);

      this.restore();

   }

   this.restore();

}

Sample usage:

var ctx = document.getElementById('canvas').getContext('2d');

ctx.font = bold 30px Serif;

ctx.fillTextCircle(Circle Text ,150,150,75,Math.PI / 2);

The extra space at the end of the string adds some extra padding.

Sample output: