In the technology demonstrations at Oak Hill last night, one of the teachersat the Smartboard demo

indicated that she could really use a graphing calculator that they could display
on the Smartboard.  Microsoft has a very nice, simple graphing calculator,
as part of the Windows XP "PowerToys" available as a free download
from here.

(Unfortunately, it doesn't install on Vista, which probably menas it won't install on Windows 7 either, although it works fine if you can get it installed.  There's a simple workaround here.)