[nerv_]

<img src="http://javascript.ru/forum/images/smilies/smile.gif" style="position:relative;">

<script>
	var elem = document.getElementsByTagName( 'img' )[ 0 ], i = 0,
		timer = setInterval(
			function() {						
				if ( i === 400 ) clearInterval( timer );
				elem.style.left = i + 'px';
				i += 2;
			},
			30
		);
</script>