This Drupal module will grab a user's Twitter feed and display it on your site.  The module will also allow you to manage:

This plug-in allows you to validate HTML and CSS of the current webpage on-the-fly using the W3C validation engine and the Firefox plugin called Ubiquity.  You can download Ubiquity here.  Once installed, you can simply goto command mode (alt-space by default) and type either: 'validate-html' or 'validate-css'.