I have recently run some successful trials of Wii Whiteboards, using a WiiRemote, bluetooth connection and an IR Pen. I bought an IR Pen from WiiTeachers.com and was pleased with a 2 week delivery from the US by USPS. I am more than pleased with the results so far. While I had some issues getting the WiiRemote to link with Windows I have now got a reliable method which I have shared back to the Wii forums http://www.wiimoteproject.com/. I have been quite pleased with the accuracy so far. Unfortunately I have been using a pathetic projector so will try to swap that out for one that will let be get a larger screen (this one is at the end of its bulb life so you can't see anything if you back up too far :-( which is why it needs to be changed).
The WiiWhiteboard software has been fine as the basic connection tool which I have then put together with Promethean's activinspire software, or any other programs.