Mine

<?php
session_start();

if ($mode == "submit")
{
	if (!$_SESSION['post'])
	{
		(code to enter data into database)

		echo "<meta http-equiv=\"refresh\" content=\"3; url=http://someurl.com\">";

		$_SESSION['post'] = true;
	}
	else if ($_SESSION['post'])
	{
		$page_error = "Post already submitted.";
	}
	else
	{
		$page_error = "Session variables corrupted!";
	}
}
else
{
	$_SESSION['post'] = false;

	echo "
		<form action=\"" . $_SERVER['PHP_SELF'] . "?&mode=submit\" method=\"post\">
			<label for=\"TITLE\">Title for post: </label><input name=\"TITLE\" size=\"30\" type=\"text\" /><br />
			<label for=\"USER\">Desired username: </label><input name=\"USER\" size=\"30\" type=\"text\" /><br />
			<label for=\"TEXT\">Text for post: </label><br />
			<textarea cols=\"60\" name=\"TEXT\" rows=\"20\"></textarea><br />
			<input name=\"SUBMIT\" type=\"submit\" value=\"Submit\" />
		</form>
	";
}
?>