Pirate Bay name and magnet mailer
Generally, RegExps are a bad choice to deal with HTML code. You're better of with DOM parser: parse the tree and then use XPath to find desired elements, i.e. the ones containing the torrent name and the magnet link. I'm not posting any code because I've never done it in PHP though, but as a pointer...

Anyway, if you just wanted a simple script that just works, you're good, and if you wanted to do some self-education, you can try parsing the DOM.

The first search result from Google gives me this: http://simplehtmldom.sourceforge.net/

And some points on the code style:

You have some weird (IMO) indentation in the if statement. Usually the closing bracket is on the same level as if is, i.e.:

if (mail($to, $subject, print_r($matches, 1), 'From: BlackBeard@piratemail.com')) {
    echo("&lt;p&gt;Message successfully sent!&lt;/p&gt;");
} else {
    echo("&lt;p&gt;Message delivery failed...&lt;/p&gt;");
}


And you have inconsistent spaces-after-arguments:

preg_match_all($selected,$data,$matches, PREG_OFFSET_CAPTURE);
....
mail($to, $subject, print_r($matches, 1), 'From: BlackBeard@piratemail.com')


Second one (with spaces after commas) is usually a preferred one.