function image() {
};

image = new image();
number = 0;

// imageArray

image[number++] = "<a href='http://igrezadecu.com'><img src='http://uradi.com/oglasi/300x250.png' border='0' target='_blank' height='250' width='300' title='Igre za decu - Games for Kids'></a>"
image[number++] = "<a href='http://kafalatino.com'><img src='http://uradi.com/oglasi/l300x250.jpg' border='0' target='_blank' height='250' width='300' title='Vreme je za Espresso'></a>"
increment = Math.floor(Math.random() * number);

document.write(image[increment]);