font-detect-js

Uses javascript (jQuery or Prototype) + flash to detect your system fonts.

View a demo

<!-- element for SWF to load into -->
<div id="font-detect-swf"></div>

<script src="javascripts/jquery-1.2.6.pack.js"></script>
<script src="javascripts/swfobject.js"></script>
<script src="javascripts/font-detect.js"></script>  
<script>
  $(document).ready(function() {

    var fontDetect = newFontDetect("font-detect-swf", "flash/FontList.swf", function(fd) {        
      var fonts = fd.fonts();

      // Do something with fonts, which look like: [ { fontName:'Arial', fontStyle:'regular' fontType:'device' }, .... ]
      // for(var i = 0, length = fonts.length; i < length; i++) {
      //   var name = fonts[i].fontName;
      // }
    };

  });
</script>

There is also a Prototype version at font-detect.prototype.js