Naomi Bates' site for book trailer resources. It offers information about creating good book trailers as well as where you can find resources for creating your own.
BTFA was created by Teresa Schauer, a district librarian in South Texas. Whilst creating book trailers she also discovered there wasn't really a place online to find and share other free book trailers, so decided to create BTFA.
The students at the School of Library and Information Studies at Texas Women's University have created for many trailers for the Printz Award winners and Honor Books dating back to 2000.
The site has has la lot of trailers, for all ages and interest levels, including children and young adult. They are available for viewing and embedding/sharing.