Leopard Quickview
In Mac OS Xs Leopards new feature is Quickview, lets you do is preview documents, music, videos, without launching any application.
So to use this feature in Leopard select the document or media file and press the “spacebar” now you will be able to scroll through any text or media files. When you are finished in Quickview hit the spacebar again to close. Quickview is only for viewing files, you will not be able to edit files within Quickview.