I have been using the tip-switch pen for awhile and it seems to work great for writing on a white board with a projected image.  With a tip switch, you don't have to worry about coordinating the writing with pressing a button.  You can see my earlier post about the pen or look here for pictures  http://stru.calvin.edu/WiiProject/index.htm

So far, the pen has a Vishay TSAL6400 IR-Led, (2) 1.5 volt type "N" batteries a resistor and a tip micro-switch. I opted for a 3 volt system to have something that would not be too sensitive to battery drainage.

I have been using the "Wiimote Smoothboard" software with two wiimotes (one on the left and one on the right of the whiteboard - mounted about 4 feet off the ground.) I used the Smoothboard option to Activate Smoothing (under the Cursor Control tab).http://www.boonjin.com/wp/

I have also been working with Jarnal http://www.dklevine.com/general/software/tc1000/jarnal.htm which is a note taker and PDF annotator.

I lent the pen and wiimote system to a colleague who used it for a presentation\meeting.  He had never used the system before and used it to animate a power point presentation during a long meeting.   He said that it worked great but then after an hour or so he found that the IRpen was not longer calibrated - it seemed that the calibration drifted.

I am not sure if the calibration actually drifted or possibly one of the wiimotes got bumped.  I will now try to find a better mounting system to stop the wiimotes from moving.

Has anyone had problems with the calibration drifting?