Shi-neks are itty-bitty undead slug-foot-things that form when wendigo feet burn off... yeah. One of the stranger ideas I've ever had. Anyway...
Ability Scores: Shi-neks gain a +2 bonus to ALL of their mental scores, as well as a hidden +2 to Dexterity from their size. So what's the downside? An absolutely massive -6 to their Strength. Shi-neks are never going to excel as melee combatants, but they're decent at range, and they shine as any spellcaster. Since they're undead, they don't have a Constitution score.
Size: Shi-neks are Tiny. While this does give them a +2 to their AC, +2 to hit and a hidden Dexterity bonus, it also means that they have no natural reach. You have to move INTO enemy squares for melee combat, which provokes attacks of opportunity. So what are you doing going into melee as a shi-nek?
Type: Shi-neks are undead, so they don't have a Constitution score. Everything that's normally based on Con instead comes from Charisma, so you'll want to keep that fairly high. Also, if your character dies, you can't be raised, so always keep in mind that retreat is an option. In addition, mental effects would normally have no effect on them, buuuut...
Fear Response: They have this trait. Not only are they susceptible to mental effects, they actually take a penalty on saves against fear. However, this does mean that the little feety people can make use of morale bonuses, so cavalier banners and other such effects still work on them.
Speed: This is how I punish you for all the awesome parts of being a shi-nek. You can only move ONE SQUARE per turn, and unlike merfolk, there's no alternate means of movement to offset this. You're either going to want a mount, or to hitch a ride on one of your adventuring buddies. Even the fact that shi-neks are immune to tripping doesn't offset this by much; when was the last time your character was tripped?
Resurrection Vulnerability: Don't panic! You're not going to die instantly if someone casts raise dead on you! Due to a trait I'll be discussing later, you essentially get two saves to resist.
Neutral Necromancy: Has it ever bugged you that the mindless zombies and skeletons are somehow evil? Here's how you remedy that! With this, your undead thralls are True Neutral.
Timid: The best part of being a shi-nek. Not only do they get a +2 to Perception, they also get it and Stealth in-class. Very nice!
Twinned Creature: This is mostly fluff, but it's fitting fluff. Also, it essentially means you get to make two characters, even if you don't use both of them. In addition, this twin ALSO gets a saving throw when you're hit by a raise spell; you only go poof if BOTH saves fail.
Alternate Racial Traits:
Alchemist: The hidden Dex bonus and obvious Int bonus mean that you're probably going to want to throw bombs. No mutagen is going to counteract your positively crippling Strength score.
Barbarian: HAHAHAHA WHAT
Bard: Shi-neks get bonuses to both Intelligence and Charisma, so they're decent as bards. Just don't expect to be doing much yourself.
Cavalier: I'm really going to have to think up some Small mounts for a shi-nek cavalier, but anything to counter that god-awful speed.
Summoner: Not only do shi-neks do well as normal summoners, they also have a racial archetype, the Necrocrafter, that's full of flavor and fairly powerful.