I agree with all the links above - PHP Freaks being my favourite.  Some others are:
http://php.resourceindex.com/
http://www.php.net/manual/en/ - True not a tutorial but it's invaluable!
And for a super quick tutorial... 
- Open Notepad.
 - Enter the following:
	Code:
	<html>
<head>
<title>My First PHP Page</title>
</head>
<body>
<?php
echo 'Hello World!';
echo '<br/>';
$a = 7;
$b = 12;
$c = $a + $b;
echo "$a + $b = $c";
?>
</body>
</html>
  - Save this as test.php
 - Upload the test.php file to the folder you store your regular HTML pages
 - Point your browser to the address of your web site followed by "test.php".  For example http://www.mywebpage.com/test.php
 
You should get a page saying:
Finally try changing this line:  
	Code:
	echo "$a + $b = $c";
  to use single instead of double quotes and see what happens.