This one's body section looks like this:
<body> <h1>natas3</h1> <div id="content"> There is nothing on this page <!-- No more information leaks!! Not even Google will find it this time... --> </div> </body>
The "not even Google" part is probably a reference to the robots.txt file used to restrict bots & spiders.
Looking at http://natas3.natas.labs.overthewire.org/robots.txt shows there's secret, hidden directory called "/s3cr3t/"
Browsing there, we find another users.txt file.