<!-- random images -->
var page = new Array()

page[0] = 'http://www.gaj.sisco.pl/img/galeria/small/foto1.jpg'
page[1] = 'http://www.gaj.sisco.pl/img/galeria/small/foto2.jpg'
page[2] = 'http://www.gaj.sisco.pl/img/galeria/small/foto3.jpg'
page[3] = 'http://www.gaj.sisco.pl/img/galeria/small/foto4.jpg'
page[4] = 'http://www.gaj.sisco.pl/img/galeria/small/foto5.jpg'
page[5] = 'http://www.gaj.sisco.pl/img/galeria/small/foto6.jpg'
page[6] = 'http://www.gaj.sisco.pl/img/galeria/small/foto7.jpg'
page[7] = 'http://www.gaj.sisco.pl/img/galeria/small/foto8.jpg'
page[8] = 'http://www.gaj.sisco.pl/img/galeria/small/foto9.jpg'
page[9] = 'http://www.gaj.sisco.pl/img/galeria/small/foto10.jpg'
page[10] = 'http://www.gaj.sisco.pl/img/galeria/small/foto11.jpg'
page[11] = 'http://www.gaj.sisco.pl/img/galeria/small/foto12.jpg'
page[12] = 'http://www.gaj.sisco.pl/img/galeria/small/foto13.jpg'
page[13] = 'http://www.gaj.sisco.pl/img/galeria/small/foto14.jpg'
page[14] = 'http://www.gaj.sisco.pl/img/galeria/small/foto15.jpg'
page[15] = 'http://www.gaj.sisco.pl/img/galeria/small/foto16.jpg'

function showImage(tabname){
tab = eval(tabname);
var p = tab.length;
var whichImage = Math.round(Math.random()*(p-1))
document.write('<img border="0"  src="'+tab[whichImage]+'">');
}
<!-- random images -->