This site from PBS is a great resource to teachers of all grade levels. It's free to create an account (if you don't, you only get to view 3 resources). Once you're in, you can select the grade levels, subjects, media type, languages, and accessibility to narrow your resources.
There's a lot of playing around to do on this site because there are tons of resources here! New features coming soon to this site are National and Common Core curriculum standards, teacher-managed classroom pages, and more!