I've just finished a three day country school tour, visiting clients and demonstrating technology to new schools.
I'm constantly asked for resources for lower primary - so here are a few new ones as well as some old favorites.
iBoard -a free website specifically for use with an IWB and specifically for lower primary. The iboard is perfect for warm-ups as well as a main teaching point resource. It's all in Adobe flash so can run on any board (including eBeam), and is grouped by subject area and grade level.
Starfall - A graded site for early reading, again free. lots of colour and good use of sound. Perfect as an interactive bigbook on your IWB.
Crickweb - Another graded site - this one has interactive for IWB's from lower primary right through to lower hight school. A bit of advertising on the main page but otherwise and excellent resources
topmarks - Yet another UK site. This one is very comprehensive and has a huge range of interactives with lesson ideas as well.
BGfL - yep another UK site. This one is set up by the Birmiham Grid for Learning. A great collected work of some of the best flash interactives around. All sorted by subject groups
Scootle - If you are in an Australian Government, Catholic or even at some idependant schools, you have access to scootle. Designed by the Learning Federation with funds from the federal government. Scootle/learning federation resources cover a huge range of subjects and levels. Government and Catholic schools usually access this site via their portal - in the case of WA its the DET portal - then look for the learning federation resources.
There is more - let me know if you have found any that you use on a constant basis.