Loki is playing with his busy buddy twist n treat right now. It's purple and looks like a flying saucer. You fill it with kibble or small treats and then screw it together. Sometimes I take half of his breakfast and take it out of his bowl and put it in there, then set it next to his half full bowl. He will take the toy over eating the food already in his bowl. He'd rather work for it than get free food!
There are lots of toys that dispense treats. I also have a big ball thing from Loopies that has like 10 small soft balls inside. Loki has to work to get the balls out. That one is fun too!
I wish there were more out there. Terriers are smart and like puzzle toys.
http://www.busybuddytoys.com/