Here is a simple jQuery script for styling links by file type.

$(document).ready(function() {

$("a[href$='.pdf']").addClass("ss_sprite ss_page_white_acrobat"); 
$("a[href$='.txt'], a[href$='.rft']").addClass("ss_sprite ss_page_white_text");
$("a[href$='.doc'], a[href$='.docx'], a[href$='.odt']").addClass("ss_sprite ss_page_white_word");
$("a[href$='.xls'], a[href$='.xlsx'], a[href$='.ods']").addClass("ss_sprite ss_page_white_excel");
$("a[href$='.ppt'], a[href$='.pptx'], a[href$='.odp']").addClass("ss_sprite ss_page_white_powerpoint");
$("a[href$='.gif'], a[href$='.png'], a[href$='.jpg']").addClass("ss_sprite ss_image");  
$("a[href$='.svg'], a[href$='.ai'], a[href$='.cdr']").addClass("ss_sprite ss_vector");
$("a[href$='.zip'], a[href$='.rar'], a[href$='.7z']").addClass("ss_sprite ss_page_white_zip");
$("a[href$='.tgz'], a[href$='.bz2'], a[href$='.tar.gz']").addClass("ss_sprite ss_page_white_compressed");
$("a[href^='mailto:']").addClass("ss_sprite ss_email_edit"); 
$('a').filter(function() {
    return this.hostname && this.hostname !== location.hostname;
  }).addClass("ss_sprite ss_link").attr("target", "_blank");

});