It’s not that often that a nifty piece of free educational software comes along! 
GeoGebra is a great resource for the classroom and well worth the time it takes to master its use. It is a Mathamatics software program, a winner of several awards worldwide, and ideal for Post Primary and beyond use. However it also has a number of features that slot right into the Primary School Revised Curriculum. Available for four platforms, Mac, Windows, Linux and other Java based platforms, GeoGebra has a straight forward install process and you can be up and running in a few minutes. It works great as a resource on an Interactive White Board. After using it for a week or so in the classroom I found it helpful to turn off the Axis and Algebra view from the main menu so as to make the interface less distracting for the pupils as they view it on the IWB. The support tutorials are clear and easy to follow and you can soon begin to draw perpendicular and parallel lines, triangles, angles, regular polygons and circles (with or without showing radius). 
Once drawn, these objects can be exported to web pages.
Check it out for yourself at GeoGebra. The Regional Centre for Excellence in Mathematics Teaching and Learning at the University of Limerick have some great resources for GeoGebra; check these resources here.
I intend to spend some time on the tutorials for GeoGebra and hope to be able to create some Maths resources for my class. This screenshot showing the use of GeoGebra to support the teaching of fractions is something that I would like to be able to reproduce myself!