Here's the list of familiars I had laying around on my computer. Some of them come from outside sources, some of them I made up. None of them have been playtested, so some of them might be too powerful,
Butterfly Familiar: A butterfly familiar grants its owner a +1 to all of his or her spell DCs.
Badger or Skunk Familiar: Gives master +2 to Escape Artist checks
Bat Familiar: Gives master +2 to Listen checks.
Brain Mole Familiar: Gives master +2 to Knowledge (Psionics) checks
Canary or Songbird familiar: Gives master +2 to Perform checks
Carp, Piranha, or other Fish familiar: Lets master go two more hours without dying of dehydration
Cat or Fox Familiar: Gives master +2 bonus to Move Silently checks
Chameleon or Pseudodragon Familiar: Gives master +2 to Hide checks
Chicken, Turkey, Dodo, Swan or Duck familiar: Gives master +2 to Search checks
Crab or Lobster Familiar: Grants master ability to see as well underwater as on land
Dove Familiar: A dove familiar grants its master a +2 bonus to Charisma score.
Earthworm Familiar (Diminutive): Gives master a 5 foot burrow speed
Elemental (Tiny) Familiar: Grants master +2 bonus to any checks involving the appropriate element.
Gecko Familiar: A gecko familiar grants its master darkvision 30’.
Gopher or Groundhog Familiar: Gives master a 5 foot burrow speed
Hamster or Guinea Pig Familiar: Gives master +2 to Wilderness Lore checks
Hawk Familiar: Gives master +2 bonus to Spot checks
Hummingbird Familiar: A hummingbird familiar grants its master a +2 bonus to his or her Dexterity score
Iguana Familiar: Gives master +2 to Climb Checks
Mole or Vole Familiar: Gives master a 5 foot burrow speed
Monkey or Lemur Familiar: Gives master +2 to Pick Pocket checks
Monstrous Scorpion, Spider, or Centipdede (Tiny) Familiar: Gives master +2 to poison DCs
Mouse Familiar: Gives Master +2 to Hide checks
Otter or Beaver Familiar: Gives master +2 to Swim checks
Owl Familiar: Gives master +2 bonus to Move Silently checks
Pig or Corgi: Gives master Scent Extraordinary ability
Porcupine or Hedgehog Familiar: Gives master a +1 bonus to ranged attacks
Rabbit or Hare Familiar: The rabbit familiar grants its master the Run feat for free. If the master already has this feat, the rabbit grants an extra 10’ to the movement rate of its master.
Rat, Raccoon, Shrew or Opossum Familiar: Gives master +2 bonus to Fortitude saves
Raven, Crow, Toucan, or Parrot Familiar: Speaks one language
Squirrel or Chipmunk Familiar: The squirrel familiar grants its master a +2 bonus to all Balance checks.
Tarantella Familiar: A tarantella familiar grants its master a +2 bonus to Craft checks.
Toad or Frog Familiar: Gives Master +2 to Constitution score
Turtle or Tortoise Familiar: A turtle familiar reduces the armor check penalty of its master by half (to a minimum of -1).
Viper, Asp, or other Tiny Snake Familiar: Poisonous Bite
Weasel, Mink, or Ferret Familiar: Master gains +2 bonus to Reflex saves
Zombie or Skeleton (Tiny) Familiar: --
