Rather than stacking crates for storage, turn them on their side and into a brightly colored display. Pick colors that will contrast with the contents or let each family member choose a color and curate his or her own shelf.
Using a paint and paintbrush, paint the inside of each box and allow each to dry fully.
Mark where you would like your boxes to hang on the wall and drill each into place using an anchor and screw.
Fill with souvenirs, keepsake toys or other items you want to show off.