text = new Array(2);

text[0] = "<a target='_blank' rel='nofollow' class='mainlevel-nav' href = 'http://www.lynxtrack.com/click/6fdl8zt8CsF84Dkqq/s-SID'>Free Macbook</a>";
text[1] = "<a target='_blank' rel='nofollow' class='mainlevel-nav' href = 'http://www.lynxtrack.com/click/bkN20cT05cd0gV1MM/s-SID'>Free IPad2</a>";

index = Math.floor(Math.random() * text.length);
document.write(text[index]);