The main advantage of modular furniture is that you can pick the components you need, in the numbers you need, and combine them in the way that is most practical or most attractive to you. When it comes to modular storage, you will find sets that feature simple cubes, shelves and drawer units which you can stack according to the space available to you, and of course according to your budget.
I like the clean, white look of this version:
Modular bedroom storage:
Modular bedroom storage pictured: Foremost 340001 Modular 5-in-1 Shelf Cube Storage System, White