Saludos!
Código:
<script language="JavaScript"> var rnd; var getRandom; var blogTitle; var randomTitle; var titlePath; var maxNumberHeader; var nomBanner; var extBanner; getRandom = false; maxNumberHeader = 405; titlePath = "Random/"; nomBanner = "0"; extBanner = ".JPG"; rnd = Math.random(); rnd *= maxNumberHeader; rnd = Math.round(rnd); randomTitle = titlePath + nomBanner + rnd; blogTitle = "<img src='" + randomTitle + extBanner + "' alt='Imagenes al Azar' border='0' width='112' height='83'/>"; document.writeln(blogTitle); </script>