Free Online Collaborative Whiteboard, K-12

http://cosketch.com/
This is a multi-user online whiteboard tool designed to give users the ability to quickly visualize and share their ideas as images. Anything they create will show up for all other users in real time. Just click once to save a sketch as an image for embedding on forums, blogs, or other digital files. Like the name implies, users can collaborate using different draw and shape tools and they can type messages in a collaborative fashion. The originator can pick from several backgrounds, upload a picture as a background, or use maps found in Google Maps as the background. This collaborative tool also includes a chat window so all users can chat as they sketch, type, and use various shapes and stamps. This tool can be used to encourage students and colleagues to brainstorm ideas, share a sketch, collaborate on a drawing, mix pictures with text, or import a background and share.