There is an interesting Whiteboard tool that Norma told me about called Dabbleboard which one could use in conjunction with an LMS simply by linking to it. Each particular whiteboard get's its own unique url. While Dabbleboard does allow a login, it can be accessed anonymously. And the boards can be kept private so anyone outside the class wouldn't use it. It does seem to be a step up from the whiteboards that are in the LMS.
The Chat tool that accompanies Dabbleboard is actual a different product, Tokbox, which does voice and video chat in addition to the standard text chat, all through the browser without a dedicated client. It also allows video mail, a function I expect will grow dramatically in the next year or so.
Not everything works with these tools. We've tried embedding the Dabbleboard and the chat doesn't seem to function this way. Also that place where you change your name online appears flaky. But it does seem promising. I hope they keep developing it.