FontAvailable is a short and brilliant jQuery plugin (put together by Howard Rauscher), that allows to check if ceratin font is installed on a visitor’s computer/device. Why, you ask? So you can select an adequate method of enhancing your website/webapp typography (@font-face, sIFR, typeface.js, cufón, etc.).
$(document).ready(function() {
if($.fontAvailable('klavika')) {
// @font-face
}else{
// sIFR / typeface.js / cufón
}
});