Maybe you like this one as a starter - here I have tweaked the newssite
heise to nearly perfection - you can clearly distinguish links and see if they were visited or not and if they are external links.
If you like I can make a screenshot later.
@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("heise.de"){
a:link {text-decoration:none !important; font-weight:bold !important; color:blue !important;font-family:times;text-shadow: #c0c0c0 3px 3px 5px;}
a:visited {text-decoration:none !important; font-weight:normal !important; color:navy!important; text-shadow: #c0c0c0 3px 3px 5px;}
a:hover {text-decoration:none !important; font-weight:bold !important; background-color:gold !important;}
a:active {text-decoration:none !important; font-weight:bold !important; background-color:blanchedalmond !important;}
a:focus {text-decoration:none !important; font-weight:bold !important; background-color:aqua !important;}
#body, html {font-family:times !important;}
body, html {font-family:dina !important;font-size:10pt !important;}
a[href^="http:"] {
text-shadow: red 3px 3px 5px;
}
a[href^="http://heise.de"],
a[href^="http://www.heise.de"]{
text-shadow: #c0c0c0 3px 3px 5px;
}
}