Liteboard is a shareable interactive whiteboard with videoconferencing capabilities. It is free and doesn’t require an account for you or your students.
Once you create a lecture, you are given a link that you share with your students. They can then see the board in realtime. If you share your microphone and/or webcam, they can also see and hear you.
Drawing with the mouse is a little wonky, so a touchscreen laptop or an interactive whiteboard would help.
I love how you or our students don’t need an account to use the site. One thing to be aware of, the drawing tools are pretty limited, and there is no confirmation of clearing the current board or all of the boards. You also can’t turn off the text chat.
All in all, this is a very useful site!