When your child receives something new, they should have to give one of their old toys to a thrift store, or a friend. It keeps clutter down to a minimum. It also teaches them to not overdo it as they get older.
This page contains the following solutions.
To organize my girls smaller toys, I filled see through bins with the toys, took a picture with my digital camera of one or two of the items that were inside (for example) jewelry or little people.
The outside of the refrigerator makes a great Bakugan play area. Bakugans stick to the refrigerator with their magnets. You can line them up, battle them, and make them climb up the refrigerator.