Since I switched to Safari as my main browser, I notice these cute search input boxes from time to time. They don’t look like regular textfields but have rounded corners and take (among others) these additional parameters:

• placeholder="Text": Like the attribute says, a placeholder text can be defined. That means that a grey text appears when the field doesn’t have the focus and is otherwise empty.
• autosave="id": Saves a history of the search terms the user entered. The list is shared among all inputs with the same autosave id. It is advised to use a certain format for the id.
• incremental="uri": This allows Spotlight-like find-as-you-type behavior. Unfortunately, this is completely undocumented. It is not known what format the return value should have.

I always liked this input box and intended to use it with my new theme. However, the value search is non-standard which made me keep away from it. Instead, I wrote a Drupal module that adds a JavaScript file which in turn changes the type value of Drupal’s search boxes to search.