With 9 in the family, I wasn't overly concerned that we went through a whole roll of toilet paper until I saw what my 4 year old left on the floor. To borrow the words of Glenn Beck "It made blood want to shoot out of my eyes". So when I realized she just didn't know how much TP to use, I came up with the solution of "wiping squares" for her.
Since some women make their own sanitary pads, and babies use reusable cloth diapers I made some flannel squares that are just the right size for her to wipe with-and purple to boot. She has a special bucket by the toilet to toss them in and then I just throw them in with the towels or a load of laundry. I just cut 3 layers of flannel into 3 inch squares and zig zag sewed them together on my sewing machine. I only let her use them for tinkling, but that alone should save us huge!
My other daughter wants some of her own now too. :) We're feeling like we've gone so "green" with our washable toilet paper in pretty colors. At $2.97 for a yard of flannel I can make around 30 of them.