| Katydid |
Noble animals are intelligent, talking animals introduced in a 3.5 third-party splatbook, converted for Paizo a year or two ago and partially available on the PFSRD.
The animal selection is huge and allows several interesting things to be done, though the text limits you to Core classes only. Most animals have some form of Wis bonus and are nonproficient in armor (dogs, elephants and horses can wear barding) and weapons, but gain various bonuses from Deeds - basically an alternate set of feats you only get by spending XP and meeting the Deed's requirements.
Currently, I'm thinking the armour nonproficiency lends itself to casters. As an animal you can also get humanoid familiars/companions - which opens up some completely hilarious possibilities.
But, what do you think would be some interesting things to build as an animal PC?