Last time we were in Petco, I randomly grabbed something called a "Monkey Tail" teaser. (Page down for a picture.) That's what its official name is, but it looks like a giant fuzzy caterpillar to me.
Billy loves it. He hasn't been this excited about a toy since he first discovered pom-poms. (Which he still loves, but not as much as his fuzzy caterpillar.) He growls, he hisses, he leaps tall cat towers in pursuit.
Even better for the humans, it's pretty durable and has so far survived the abuse more or less intact. We have a winner!