I bet you have lots of wall space in your garage - doing anything with it? 

How about an art gallery of your kids' master works. The items come home in droves, so how about displaying for a bit, and then it's easier to let it go once it's been admired for awhile. 

My boys loved this when they were younger as we saw the gallery everytime we came and left the house. I loved it since we could brighten up a normally dull spot. 

Consider this for use in a hallway to a rec room/kids play room or anywhere there is some wall space a bit underutilized, but that you can string some yarn or ribbon between two tacks. Then paper clips and the masterpieces are all you need. 

I also love this for older kids/offices/craft rooms where photos, cards, reciepts, tickets, etc., could be clipped up and kept handy. Remember to take a photo of the gallery each time you switch it out for the keepsake, and then it's easy to make peace with letting some of the items go.