When Zoe was little we used to put regular kibble in hers so that it was healthy food, not just treats, and would still keep her entertained. She learned quickly that kibble falls out really easily if you just pick up the Kong and throw it, and she still tries that with all of her treats today.
Kong also makes a frisbee. It has been a lifesaver at our house. The dogs love to play frisbee, and it usually goes like this:
1- We throw frisbee
2- Zoe runs faster than Damage and catches it
3- Zoe starts to bring the frisbee back, when Damage finally catches up and tackles her
4- Zoe and Damage play tug-of-war with the frisbee while both attempting to bring it back to us
5- When they get close, Zoe gives up and lets Damage keep the frisbee
6- We have to tell Damage "Release" so that he will drop the frisbee and we can start over (he is quite lazy and doesn't really like the running part of this process)
Because of the tug-of-war, frisbees used to last us a couple of days (if that). The Kong frisbee lasts for months! It is one of the pups' favorite activities (well, Zoe's at least) and we try to play with them every day. It's a lifesaver!