I found Kami a year ago or so, but never really needed to use it as I taught my students how to use Diigo, which allows for annotations by teachers and students. However, this year for some strange reason, I did not take the time to teach them how to use Diigo, so the annotations in readings and website was difficult.
Kami basically allows you to highlight, add post it notes, text boxes, and more. Check out the chrome extension if you think this might help you in your classroom.
I will update you on how the kids like this software and if it meets my needs.