Got one for you; From the 3.0 Sword and Sorcery Studio's Creature Collection: the Dweller at the Crossroads. an NPC / Critter / Manifestation of of a trickster. As-written, the Dweller is a CR 6 who grants Wishes, (Yes, this book WAS written before the monster manual) but his fluff paints a much more sinister (and far better) picture. Imagine if this manifestation was more of an oracle than a genie? It could show people the proper pathway to take to fulfill their quest, instead of just giving them the object of their desire...
There's a second one: Tanil's Fox. Again, poorly designed, but appropriately flexible: Tanil's fox is a tiny animal (1d8 hp) with superhuman armor class (31 AC) divine saving throws (+12 reflex!) and enough stealth and guile to avoid being caught, the 200 foot per-round movement rate dosn't hurt either. Try adding the pelt of an animal that could only be killed if you were DESTINED to kill it to your weapon!