Some of these ideas use longer tubes, like paper towel ones...hope that's ok!
Use them to be the turrets of castles.
Decorate, fill with rocks, seal both ends, and use it as a paperweight.
Decorate them like people (they will look kinda like nutcrackers, yk?)
Attach different lengths of string with little bells on the end, and hang like a wind chime.
String 3-5 together horizontally like a Choo-Choo train.
Bend a wire hanger into a circle, leaving the hook part intact. Attach the tubes all around, making a wreath.
Decorate like planes and rocket ships.
Build a log cabin.
Cut into 1.5-2 inch segments for napkin rings.
String two together with yarn about 10 feet long, and make a telephone.
Gather 10 tues, fill with rice half way, seal both ends and use for bowling pins.
Arrange 3-4 tubes of different heights on a foam tray (like one used to package ground beef) and make a desk organizer for pens, paper clips, ect.
Use one as the top to a mobile, attach 3 peices of yarn onto the side and attach little pictures to the end of the yarn.
Use one for the staff of a flag.
Fill one with little treats and wrap the whole thing up in shiney paper, like those traditional (Hawaiin?) Christmas gifts.
Make one a vase for fake flowers.
Paint one black, and use it for the body of a butterfly. THe wings can be made of paper plates.