Check out Chalk.com - a "Google Apps for teachers". Has tens of thousands of teachers using it. Its free for a teacher to use. Schools can pay to enable coll

Check out Chalk.com - a "Google Apps for teachers". Has tens of thousands of teachers using it. Its free for a teacher to use. Schools can pay to enable collaboration features. Superficially it looks like a LMS, but usually exists alongside them. (i'm not affiliated, but have been impressed by the founder. They are bootstrapped)