After getting them checked by the vet ensuring they are ok, Kylie LOVES the Purina Right Bite Hairball treats. I think they are tuna flavor. I notice if she doesn't get them regulary (which she would like to be everytime I walk into the kitchen!) she leaves me presents!
There is also some stuff called catlax or a hairball treatment. Cats are supposed to love the taste, you put it on their paw and they lick it off. Kylie hates it and flings it all over the kitchen so it is a BATTLE to get her to take it!