siteShowing=0;
var numSites=8;
siteArray = new Array(numSites);
siteArray[1]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/0452269989/rundown\"><IMG SRC=\"http://run-down.com/images/ads/book_toughness.gif\" border=\"0\" width=\"100\" height=\"148\" ALT=\"The New Toughness Training For Sports\"></a>"
siteArray[2]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/0915297019/rundown\"><IMG SRC=\"http://run-down.com/images/ads/book_once.jpg\" border=\"0\" width=\"89\" height=\"140\" ALT=\"Once a Runner\"></a>"
siteArray[3]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/0875964575/rundown\"><IMG SRC=\"http://run-down.com/images/ads/book_pre.gif\" border=\"0\" width=\"100\" height=\"155\" ALT=\"Pre!\"></a>"
siteArray[4]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/0880117354/rundown\"><IMG SRC=\"http://run-down.com/images/ads/book_daniels.gif\" border=\"0\" width=\"91\" height=\"140\" ALT=\"Daniels Running Formula\"></a>"
siteArray[5]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/1558214208/rundown\"><IMG SRC=\"http://run-down.com/images/ads/book_quotable.jpg\" border=\"0\" width=\"100\" height=\"122\" ALT=\"The Quotable Runner\"></a>"
siteArray[6]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/1891620398/rundown\"><IMG SRC=\"http://run-down.com/images/ads/book_taboo.jpg\" border=\"0\" width=\"93\" height=\"140\" ALT=\"Taboo: Why Black Athletes Dominate Sports...\"></a>"
siteArray[7]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/0790739283/rundown\"><IMG SRC=\"http://run-down.com/images/ads/without_limits.gif\" border=\"0\" width=\"79\" height=\"140\" ALT=\"Without Limits (Prefontaine)\"></a>"
siteArray[8]="<a target=\"_blank\" href=\"http://www.amazon.com/exec/obidos/tg/detail/-/6304612982/rundown\"><IMG SRC=\"http://run-down.com/images/ads/prefontaine.gif\" border=\"0\" width=\"77\" height=\"140\" ALT=\"Prefontaine\"></a>"

function randSites(){
   // Make sure you don't show the same site 2x in a row
  prevSitesShowing = siteShowing;
  while(siteShowing == prevSitesShowing)
    siteShowing = Math.ceil(Math.random() * numSites);
 }
randSites();
document.write(siteArray[siteShowing]);