Prevent anchor behaviour

This is a nice approach, if you're using jquery you can also do:

<a id="link" href="javascript:void(0)">link</a>

<script type="text/javascript">
   $("#link").click(function(ev) {
       ev.preventDefault();
   });
</script>

preventDefault can be useful also to prevent submitting form

An example of a gracefully degrading solution:

<a href="no-script.html" id="myLink">link</a>

<script>
document.getElementById("myLink").onclick = function() {
    // do things, and then
    return false;
};
</script>

Demo: http://jsfiddle.net/karim79/PkgWL/1/

You can also have this:

<a href="#" onclick="return false;">link</a>