Many great sites like YouTube, iFilm and NowPublic allow their media assets to be served to 3rd party websites (like this one). They usually offer snippets of code to be embedded in a web page that will then load a media object (usually Flash) from their servers. This module lets your site users embed such snippets into posts but gives you the power to decide which hosts to trust.
The Paranoia module attempts to identify all the places that a user can evaluate PHP via Drupal's web interface and then block those. It reduces the potential impact of an attacker gaining elevated permission on a Drupal site.
The SpamSpan module obfuscates email addresses to help prevent spambots from
collecting them. It is based on the technique from spamspan but has undergone major modifications, as the original spamspan code hasn't been updated since 2007.
This module acts as a digital notary for Drupal; it creates notarized/certified timestamps for content. When normal Drupal content is created, an easily modifiable timestamp is created.