We have a storage system like this one from IKEA in our playroom. You can mix and match the sizes of the storage drawers and shelving units.
http://www.ikea.com/us/en/catalog/products/S49857543
We have the Trofast system from IKEA in DD's bedroom. They have it in both white laminate and natural color solid pine. There are quite a few pieces that you can mix and match. It's not really cheap, but the pieces we bought are versatile and should last DD through her teen years. After that, I'm sure we'll find a place in the basement or garage to use it for storage. We got the pine wood one, and it's super durable. I sit on it all of the time, so it's pretty sturdy.
DD is only 15 months old, so she doesn't have a lot of toys in the bedroom right now (they are mostly in our living room). So, right now I have diapers, wipes, blankets, clothes, etc stored in it.
I have 2 of the pyramid pieces (pic below), and a larger piece in the middle that has a removable diaper changing table on it. The plastic bins come in different sizes and colors, so you can buy what you need. Or, you can buy wooden shelves that slide into the grooves. The larger piece that I have in the middle has since been discontinued, but I'll post a pic of one that is kind of similar to it (mine is taller). There are really a ton of ways you can customize the Trofast system. If you add some L-brackets, you can stack the pieces on top of each other. Of course, for safety reasons, it's a good idea to use furniture straps to anchor tall pieces to the wall. If I remember correctly, IKEA provided furniture straps in the box already.
