Buster & Bailey have recently been introduced to Busy Buddies & LOVE THEM - they really like the bouncy bone,, with or without a treat. Here's the link to see the toys:
http://www.busybuddytoys.com/View.aspx?page=dogs/products/toys/busybuddy. I bought them the Bouncy Bone (with extra treats) & the Twist n Treat at our local animal health center but they are sold all over the place. My pups love their kongs too but get bored with them after they get the treat out. I too am looking for more toys to keep them from getting so bored while I'm at work & they're home alone. I've heard good things about the Hide-a-Toys but haven't gotten any of those yet since they're not sold in my area. You can check out this thread too, there were some good suggestions that I have on "my list" to buy:
http://www.yorkietalk.com/forums/fun-toys/176636-what-toys-do-you-leave-them-when-theyre-alone.html