<SCRIPT language="javascript">

var howMany = 10
var quote = new Array(howMany+1)
quote[0]="Текст1"
quote[1]="Текст2"
quote[2]="Текст3"
quote[3]="Текст4"
quote[4]="Текст 4"
quote[5]="Текст 5"
quote[6]="Текст 6"
quote[7]="Текст 7"
quote[8]="Текст 8"
quote[9]="Текст 9"
quote[10]="Текст 10"

function rndnumber(){
var randscript = -1
while (randscript < 0 || randscript > howMany || isNaN(randscript)){
randscript = parseInt(Math.random()*(howMany+1))
}
return randscript
}
quo = rndnumber()
quox = quote[quo]
document.write(quox)

</SCRIPT>
var howMany = 10 - количество текстов;