var directory = '/static/images/';

var random_images    = new Array( 2 );

random_images[ 0 ]     = new Image;
random_images[ 0 ].src = directory + '01.jpg';

random_images[ 1 ]     = new Image;
random_images[ 1 ].src = directory + '02.jpg';

random_images[ 2 ]     = new Image;
random_images[ 2 ].src = directory + '03.jpg';

var index = 0;

function switch_img( idname ) {

	if ( ++index == random_images.length ) {
		index = 0;
	}

	document.images[ idname ].src = random_images[ index ].src;
	set_timer( idname );
}

function set_timer( idname ) {
	setTimeout( 'switch_img( \'' + idname + '\' )', 8000 );
}

Event.observe(window, 'load', function() {
    if( $('randimg') ) {
        set_timer( 'randimg' );
    }
});