Edit in JSFiddle

var labels = document.querySelectorAll(".popup"),
    total = labels.length;

for (var i = 0; i < total; i++)
    labels[i].addEventListener("click", function(){
        var enlace = this.getAttribute("data-link"),
            titulo = this.innerHTML;
        window.open(enlace, titulo, "width=750, height=550");
    }, false);

<label class = "popup" data-link = "http://www.google.com">Google</label>
<label class = "popup" data-link = "http://www.yahoo.com">Yahoo</label>
<label class = "popup" data-link = "http://www.bing.com">Bing</label>
<label class = "popup" data-link = "http://www.terra.com">Terra</label>
<label class = "popup" data-link = "http://www.twitter.com">Twitter</label>

.popup{
    display: block;
    background: lightsteelblue;
    color: white;
    width: 5em;
    text-align: center;
    margin-bottom: .5em;
    cursor: pointer;
}

.popup:active{
    background: lightcyan;
}