Love this idea at Eclectic Mom for covering brown paper bags with duct tape to make totes! Although they were created as Easter baskets I think they would be useful year round. This would be a great party craft for tweens too!
I think these origami bunny boxes at Origami Spirit are so cute and a great way to decorate for spring or Easter. Origami can always be a little tricky so you may want to practice a few times before showing the kids. This link is a video tutorial which is really helpful too.