Your local phone book is great for shredding. Remove any loose parts such as bells. Rabbits like toys they can easily grip with their teeth and toss around. Bird toys that can be tossed, or hung from the top of the cage and chewed or knocked about are also popular. Kitty condos with ramps and windows to climb in and chew on provide hours of diversion.
Old towels are good for bunching and scooting, tearing and shredding, and arranging just so.
Dried out pinecones are a toothsome treat. Untreated wood, twigs and logs that have been aged for at least three months are acceptable. Apple tree branches can be eaten fresh off the tree, but avoid cherry, peach, apricot, plum and redwood, which are all poisonous. Untreated sea grass or maize mats from Pier One or Cost Plus come strung together in squares as inexpensive flooring and can be cut to fit your needs. Maia prefers that the mats be fixed in one place with a heavy object so she can tug at them with her teeth.