I have also seen some people that make "yarn" out of the bags. They are making things like purses and belts. Plastic "yarn" is hard to work with, it tears sooooo easy. You really have to pay attention when you are pulling the plasitc thru the holes. Not sure about using it like real yarn for a purse or belt, haven't done those.
I did this project last year. I am thinking of making something else with plastic bags. I saved alot, and I do mean alot, of bags.