• HTML
• JS

HTML

<div style="position:relative; height:145px; margin-bottom:30px;">
    <div id="Ojo1" style="width: 132px; height: 143px; background: url(http://lh6.googleusercontent.com/-G1SdIK4EQAM/Tq9KUlmQhWI/AAAAAAAAB1k/TYW2FbzqSU8/s143/ojo1.png) center center no-repeat; position:absolute; left: 377px; top: 20px;">
        <img src="http://lh4.googleusercontent.com/-naCDuX03WpQ/Tq9KeZErQJI/AAAAAAAAB1w/meYDW9Y51M8/s34/pupila.png" width="30" height="30" />
    </div>
    <div id="Ojo2" style="width: 132px; height: 143px; background: url(http://lh4.googleusercontent.com/-DMZBDYo4Rn0/Tq9KUhX2nPI/AAAAAAAAB1g/aVv1zZO9HQU/s143/ojo2.png) center center no-repeat; position:absolute; left: 485px; top: 20px;">
        <img src="http://lh4.googleusercontent.com/-naCDuX03WpQ/Tq9KeZErQJI/AAAAAAAAB1w/meYDW9Y51M8/s34/pupila.png" width="30" height="30" />
    </div>
</div>

JS

EYES = {};
EYES.stack = [];
//
EYES.follow = function (eye) {
    var el1 = document.getElementById (eye);
    var el2 = el1.getElementsByTagName ("IMG");
    el2 = el2[0];
    el2.centre = (el1.offsetWidth - el2.offsetWidth) / 2;
    el2.style.margin = el2.centre + "px 0 0 " + el2.centre + "px";
    el1.maxDist = 6 * el1.offsetWidth;
    EYES.stack.push ([el1, el2]);
};
EYES.mousemove = function (e) {
if (!EYES.stack.length) {
    return;
}
//
var mouseX = mouseY = 0;
if (!e) var e = window.event;
if (e.pageX || e.pageY) {
    mouseX = e.pageX;
    mouseY = e.pageY;
} else if (e.clientX || e.clientY) {
    mouseX = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
    mouseY = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
}
//

for (var e=0, l=EYES.stack.length; e<l; e++) {
        var el = EYES.stack[e];
        var elX = elY = 0;
        if (el[0].offsetParent) {
            obj = el[0];
            do {
            elX += obj.offsetLeft;
            elY += obj.offsetTop;
            } while (obj = obj.offsetParent);
        }
        el[0].centreX = elX + Math.round (el[0].offsetWidth / 2);
        el[0].centreY = elY + Math.round (el[0].offsetHeight / 2);
        var difX = mouseX - el[0].centreX;
        var difY = mouseY - el[0].centreY;
        var dTan = Math.atan2 (difX, difY);
        var dist = Math.sqrt ((difX * difX) + (difY * difY));
        dist = Math.sin ((dist > el[0].maxDist ? 1 : dist / el[0].maxDist));
        var newX = el[1].centre + Math.round (Math.sin (dTan) * el[1].centre * dist);
        var newY = el[1].centre + Math.round (Math.cos (dTan) * el[1].centre * dist);
        el[1].style.margin = newY + "px 0 0 " + newX + "px";
    }
};

if (window.attachEvent) document.attachEvent ("onmousemove", EYES.mousemove);
else document.addEventListener ("mousemove", EYES.mousemove, false);

EYES.follow ('Ojo1');
EYES.follow ('Ojo2');