Not sure if this is the type of thing you're looking for or not... "should" work but I didn't test it.
Code:
<html>......
<form action="page_one.php" method="POST">
<p><input type="text" name="sometext" value="" size="30" /></p>
<p><input type="submit" name="subbutton" value="Submit It" /></p>
</form><br />
<?php
if(isset($_POST['subbutton']) && isset($_POST['sometext']) && trim($_POST['sometext']) != ''){
echo("<p>".htmlentities($_POST['sometext'])."</p>\n");
}
?>
.....
</html>