A great interactive isometric grid to demonstrate to the students how to draw 3D shapes. Particularly irregular shapes the students may have created using MAB.
Lots of good Internet based games: e.g Algebra puzzles which could be used to form the basis for a lesson or also could be used as an intro warm up or early finishers activity. Most activities would suit upper primary, however some extension students would benefit from playing the games.
Has a good selection of logic games e.g. factory balls and popular games, such as battleships.
Has a good selection of instructional maths videos, which look very useful.
Great post for the new doc's user and some useful tips and tools for the experienced user. Bookmark on your tool bar if you are a regular google docs user.