This is for Tim of Gothridge Manor. I reacted negatively to an idea of his to allow players interesting options because I imagined it was about power creep. But as I am wont to do, further reflection has made me do a complete 180 and totally embrace this idea of player perks.
It isn't anything knew, Jeff's Deck of Stuff is a big influence here too. Anyway, Tim mentioned a player in a campaign having an intelligent horse and I've been thinking of possible perks I could give players similar to those mentioned here. So here are a few more focusing on animals:
"You have a trained ferret. Before we start playing choose two tricks it knows how to do and one it's still learning. You should be able to call for these tricks with a few words (hide, fetch, go home, sic em!, etc.). Half of the time you ask for the newest trick your ferret will get it wrong and do one of the others."
I think the fun here is the player picking what the ferret can do, but also the potential chaos when it dances instead of sneaking, or something.
"You have a medium-sized dog that can speak and understand your language at a basic level. This is equivalent to using one verb per sentence (3). It is more intelligent than a normal dog about equal to that of a young child."
I'm not sure what the advantage should be here. A smaller dog could scout and go places a human couldn't. This would be really handy in an urban campaign where dogs are expected, but not so much in a dungeon where a dog is just as likely to become a snack as its master. Maybe a keen sense of smell and the ability to track as a bloodhound would be a boon. But you don't really need to speak with your dog for that to work. What would you want as a player?
"You have a parrot savant able to produce language with perfect pronunciation in five of your world's most common languages. Its vocabulary is limited though. Before play starts decide on five phrases it knows (Where is the gold?, Put down your arms!, Would you like to see my engravings?, etc). When you say one of the phrases to it, it will then repeat the equivalent phrase in all its languages in turn."
Again, I'm thinking the fun is for the player to have to predict what phrases they might find potentially useful. I suppose this and the ferret could be taught something new later at the expense of some gold.
Snake Spell Book
"You have a reticulated python that functions as a spell book. A crystal lens set in a brass ring allows you to read its arcane lore and cast a spell normally unavailable to you. It is twenty feet long and weighs 150 pounds (10 stone)."
This is Zak's idea. Although, he suggests dragons would be spell books, snakes more mundane. But I think the awkwardness of having to carry this around might balance out the power of it.
I'm not sure what the power should be, a randomly determined spell from the level above what the character can cast? What the hell am I thinking?! I was assuming this was for a magic-user, what if it was for any character, then any spell would be something unusual. But who would want to deal with that encumbrance for one spell? Any ideas for spells you might find worth it?
"You have a light grey cat. When it enters a room an image of the room appears as darker fur on its coat, (imagine a pinhole camera view of the room). It sneaks as a master rogue and has nine lives."
Okay, the name is sort of cheesy, I've always thought of cats as familiars for wizards, and I don't know how you are going to get a cat to scout a room you want it to short of tossing it in . . . but it just seems like it would be cool for the party to be crouching around a cat trying to decipher what the image on its fur means: "Are those bugbears!?"
One thing about all of these is that they are awkward magic items just for the fact that they are all alive and players will want to keep them that way. Maybe a reason to make their perk powers a little better than a inert magic item-- tarp, bucket, shovel, might have.
Also, the more I think about these, the more I think their power is in distributing them randomly. I don't think I would let players pick them.