I've been working on creating an interactive whiteboard for inworld lectures, lately.
At a basic level, it functions as a communal slide presenter. Allowing people to drop images into it, or delete images already in its contents. It also can change the aspect ratio of the display, to present images as 4:3, 1:1, or 2:1
With the overlay tools, a teacher or a group can highlight parts of an image. Each element brought onto the board, can be moved or changed by anyone. At the moment the tools include , filled and outline rectangle and circle, verticle and horizontal lines, XyText element, and pointer and crosshair.
This also allows the board to be used for simple mind-maps or brainstorming sessions.
At the moment the project is in beta, but you can check it out at the Port in my gallery space.