Looking for copyright friendly resources? Check here:

Images
Wikimedia Commons
Photos for Class
Pixabay
Flickr Creative Commons
Pics4learning
Everystockphoto
Pixel Perfect Digital
The Cavalcade of Digital Images
Compfight
EduPics
Classroom clipart (clipart and photographs)
PublicPhoto
Alegri
Behold
Free Media Goo
Let's CC

Music
Free Music Archive
Free Play

Free E-books
Project Gutenberg

Google Images
You can limit your search in Google to those labelled for reuse. Here's how: