[bes]

<img src="http://javascript.ru/forum/image.php?u=19820&dateline=1334914235" style="width: 50px">
<script>
document.body.children[0].onclick = function () {
	if (parseInt(this.style.width) > 100) {
		this.style.width = 50 + 'px';
	} else {
		this.style.width =  parseInt(this.style.width) + 50 + 'px';
	}
}
</script>