Your on the right track but it looks like your missing some things.
This line is the one that is sending the parameters to send.php
$.post( "send.php",
{ name: nameVal, email: emailVal, snail: snailVal, comments: commentsVal, subject: subjectVal },
As you can see, the message parameter is actually called "comments" not message.
So the first thing you should change in your send.php is the following: $_REQUEST['message'] should be $_REQUEST['comments'];
The you will see the comments appear.
Now your not seeing the name of the sender because it wasn't included at all in send.php.
You might want to do something like the following:
$message = "From: ".$_REQUEST['name']." - [".$_REQUEST['email']."]\n";
$message .= "Snail: ".$_REQUEST['snail']\n";
$message .= "Subject: ".$_REQUEST['subject']\n";
$message .= "Message: ".$_REQUEST['comments'];
This will give you something like the following example in your e-mail:
From: John Smith - [john@smith.com]
Snail: 123 Sesame Street
Subject: Love your website
Message: This site is fantastic, keep up the good work.