1. Moose Antler! My dog loves these things. They're kind of expensive but for a treat every once in awhile, can't beat them and they take forever to chew down.
2. Alligator on a string. First buy an alligator. Second buy about 25' of Paracord. Tie this to the alligator and all of a sudden you have an alligator on a string that moves by itself. Dogs' mind blown.
3. This is one of my go to options. Purchase a kong or similar toy and stuff it with whatever healthy treat you have laying around. I generally trade off between stuffing as many baby carrots in there as I can with a bit of peanut butter and stuffing a banana in there and freezing it over night.
4. Classic Benebone chew toys are great. If you're dog isn't super interested in nylabones or other similar products, a benebone comes embedded with real flavors and will keep your dog gnawing for hours.