SuperTab Supports offers you on-demand previews of certain types of files within the App Switcher:

These file types are:
  • Text Files
  • Image Files
  • PDF Files
  • Videos
    • SuperTab previews video files by playing the video right in the App Switcher. You can specify in SuperTab Settings (under "Options") whether you want audio to play during video previews or not.
    Examples
    SuperTab also uses each Image File's contents as its icon.
    SuperTab can preview plain text and rich text documents.
    SuperTab also uses each PDF's contents as its icon.
    SuperTab also previews images and PDF files when you use SuperTab to access a folder's contents.