a cat purring is one of the most relaxing sounds that i can think of. i plan on encorporating some of that into future compositions.
i haven't tracked it yet, but my neighbor has a cat that's kind of an outside cat which visits me often and is very vocal as far as felines go. i just got one of the RNP's, so i'll use it when tracking. this cat kind of invites herself in to my house a lot, so i'll just pet her a bit in front of a mic and voila - original animal sounds.