Android Buld-in Content Providers

http://developer.android.com/reference/android/provider/package-summary.html

Here are a few of the providers listed on that documentation page:
Browser
CallLog
Contacts
  People
  Phones
  Photos
  Groups
MediaStore
  Audio
    Albums
    Artists
    Genres
    Playlists
  Images
    Thumbnails
  Video
Settings