Rabbit Hole is a module that adds the ability to control what should happen when a node is being viewed. Perhaps you have a content type that never should be displayed on its own page, like an image content type that's displayed in a carousel. Rabbit Hole can prevent this node from being accessible on its own page, through node/xxx.
Allows the presence of exposed filters on a view to be controlled by values in another exposed filter. Dependent filters are hidden when not relevant, and their values are not considered when the exposed form is submitted.
The Authcache module offers page caching for both anonymous users and logged-in authenticated users. This allows Drupal/PHP to only spend 1-2 milliseconds serving pages, greatly reducing server resources.
Drupal integration with the Modernizr JavaScript library. Modernizr allows you to responsibly integrate HTML5 and CSS3 using feature detection, while providing reliable fallback behavior for older browsers.
overview drupal client-/server-side form validation modules
