Here is a cool, quiet toy called Wikki Stix. Not very impressive looking, I can assure you. However, they are totally rad. They are wax-covered pieces of yarn, I think. You can make them stick to one another and create bowls, plates, creatures, and such. They can be pressed into each other to make 3-D buildings. They can make long ropes. They stick to the wall as "frames" and art-- there was an exquisite aquarium scene on my bedroom wall for over a week and they didn't leave a mark.
At Rainbow Resource they are less than $3 for a single-color pack (no more fighting over whose Stix it is) and they also sell activity and educational kits. Claire got a set for her birthday and we loved them so much we went and got another pack so there would be enough for everybody. I paid $5 for a package of multi-colored ones at my local craft store.
So this is what Wikki Stix look like after your kids wad them into a ball, the dog chews on it, and it gets rubbed into the carpet. Never fear! I have discovered a way to restore them to their original smooth straightness.
First, untangle them and pick off any fuzz or dog hair that you can see. Then lay it straight in front of you and roll it back and forth on the table under your hands (as if you were making a Play-Doh worm). After just a few seconds it will be as smooth and pliable and mess-free as it was initially! Enjoy!
Don't leave them in the car, though. I bet they would melt into the upholstery. But they would be absolutely awesome on a plane trip.