In the search for something to store my collection of Dwarven Forge, a member of the Dwarven Forge forums mentioned the 20 litre Really Useful box. I currently have 10 of these and plan to at least double that number this spring.
The boxes are sturdy, and they stack very well. They are also a great size for Master Maze and Game Tiles pieces.
One of the boxes currently holds some of the material that will be used in the upcoming game. This was gathered together for the first session back in October when I traveled to run the game.