I found s great interactive ruler, protractor, and compass online the other day. The site appears to come from the UK, and has basic tools that would work well on the Promethean board. Click the Compass tool, adjust the size, and draw a circle on the screen. Click the Protractor to measure angles, and the Ruler to measure lines. Use Pencil tool will let you draw straight lines on the workspace while the pen will let you write free form. I like that the ruler actually portrays the 1/2 line accurately. As Promethean users might already know, these tools are also located within ActivInspire, but many teachers have issues with the way the ruler looks in Inspire. It is not the same ruler they expect kids to use in math class, but the ruler on this site provides a good alternative.