There is also a similar toy that's a ball and serves the same purpose. Kongs are great toys as well. Fill it with treats and plug the hole with a large milk bone type of treat. The dogs have to get that tight bone out before they can get the treats.
Last, sometimes dogs seem bored when they lay around, but they could be ill. Take your dog to a vet and get a good checkup. If the vet says your dog is fine, then start with the suggestions above. Check out this page for some of those great toys: Anti-boredom Toys. Good luck!