Use as unique additions to photos, especially if the person sending the greeting card is in the photo - a good way to remember the person that sent it.
Start a Christmas Memory Album and cut/paste/decoupage greeting cards for each year.
Storage Boxes for Holiday Decorations
Glue greeting cards all over the boxes you pack away your holidays decorations in and store for a year in your attic, garage, etc. When the next holiday season comes around, these boxes are easy to find and identify the holiday decorations easily!
Let children make thank you cards for their teachers to show their appreciation and hide them around the classroom so the teacher will find them every now and then.
Donate to teachers for class art projects
Toys & Playthings
Cardboard House: Use a refrigerator or other large appliance box. Cut out a doorway on one side and windows on each of the other three sides of the box. Let the kids decorate using old greeting cards.
Wash and thoroughly dry large round ice cream containers (ask Baskin Robbins, etc.). Cut out characters, scenes and paste to container. Decoupage with a clear finish.