[devote]

<div style="width: 100px; height: 100px; background: red;">Иди ко мне</div>
<script>
    function myFunc() {
        alert( "called function" );
    }

    var div = document.getElementsByTagName('div')[0],
        handler = null;

    div.onmouseover = function() {
        handler = setTimeout( myFunc, 2000 );
    }
    div.onmouseout = function() {
        clearTimeout( handler );
    }
</script>