Share My Lesson is a site that I stumbled across today while looking for fun ideas to teach pre algebra concepts. This site does ask you to sign up to access the resources. However, it is worth it. They claim to have over 250,000 lessons to access. If accurate, that is insane!
Some of the key features on Share My Lesson include the ability to create an account, share/download lessons, and lessons linked to Common Core Standards. In addition, the resources are sorted by grade levels, there are "featured lessons", and the "latest resources" on the homepage for those who may check daily.