I have added these to a separate page as they are essentially commercial rather than for information or support, like the other pages. They are the nicest I’ve seen, and certainly worth a look. These are not affiliate links nor have I used their services and the links are provided without explicit recommendation. (Updated 2015)
2015 Additions (suggestions welcome).
Montessori Supplies – UK materials available to buy for delivery. (Actual products, not just downloads!)
Links from pre 2004
Most famous for their maths rods, (similar in style to some Montessori products), there is lots to look at and absorb here.
This would be a superb place to get materials if I was in the US – maybe I still could but it is certainly ideal for ogling pictures of materials, so you can make your own!