During my quest for a solution, I stumbled upon this Jquery script that caught my attention. One unique advantage it possesses in comparison to others is its ability to adjust for both height and width.
You can find the source here:
function adjustHeights(elem) {
var fontstep = 2;
if ($(elem).height()>$(elem).parent().height() || $(elem).width()>$(elem).parent().width()) {
$(elem).css('font-size',(($(elem).css('font-size').substr(0,2)-fontstep)) + 'px').css('line-height',(($(elem).css('font-size').substr(0,2))) + 'px');
adjustHeights(elem);
}
}