Place text in center of pie chart - Highcharts
text = chart.renderer.text("My Text").add();
textBBox = text.getBBox();
x = chart.plotLeft + (chart.plotWidth  * 0.5) - (textBBox.width  * 0.5);
y = chart.plotTop  + (chart.plotHeight * 0.5) - (textBBox.height * 0.5);
text.attr({x: x, y: y});

y = chart.plotTop  + (chart.plotHeight * 0.5) + (textBBox.height * 0.25);

var textX = chart.plotLeft + (chart.plotWidth  * 0.5);
var textY = chart.plotTop  + (chart.plotHeight * 0.5);

// The width and height need to be calculated properly, so I made it a span.
var span = '<span id="pieChartInfoText" style="position:absolute; text-align:center;">';
span += '<span style="font-size: 32px">Upper</span><br>';
span += '<span style="font-size: 16px">Lower</span>';
span += '</span>';

$("#addText").append(span);
span = $('#pieChartInfoText');
span.css('left', textX + (span.width() * -0.5));
span.css('top', textY + (span.height() * -0.5));

<div id="container" style="height: 400px; width: 500px"></div>​