<form method="post" action="" id="formsend">
<input type="hidden" name="formSubmit" value="" />
</form>
<script language="JavaScript">
setInterval(document.getElementById('formsend').submit(), 300000);
</script>
<input type="submit" name="formSubmit" value="Поехали :)" />
<form method="post" action="index.php" name="form1">
</form>
<script language="JavaScript">
setTimeout("document.getElementById('form1').formsubmit()", 3000);
</script>
<form method="post" action="index.php" name="form1">
<input type="submit" name="formSubmit" value="Поехали :)" />
</form>
<script language="JavaScript">
setInterval("document.form1.submit()", 300000);
</script>