Cheap wooden boxes as containers, stacked on top of one another. They're held together by binder clips. You can buy paint from a craft store to paint them if it's in your budget; if not, colored construction paper would work great too.
pull-out shelves that you can step on to reach the top! Garage shelving idea: the lower shelves actually glide out so you can step to reach top shelved items. Then they slide back to the wall. This would be so easy to DIY!
Crate Storage: Wooden crate converted into a portable side table with storage - love this creative idea. Easy to make: Turn crate sideways, add a couple of internal dividers & screw 4 castors on the base. wheels for me)