Chest (especially leather):
bare (male) and sarashi (female, if no shirt worn). There are npc monks around Outland's Auchendoon that are either bare chested or wearing a simple chest wrap. From what I've seen, Sandrene's Invisible Vest is high on the xmog wishlist for a number of people, and a sarashi (instead of the default bra) might address whatever problem blizz has with Sandrene's being xmoggable.
Shirt:
dark turtleneck. Some head/faces look better when the neck is covered.
bracers:
- there should be bracers that don't interfere with shirts that have bell-bottomed sleeves. I think there's gloves that already work that way, but because all bracers clamp down shirt sleeves, it makes bell-sleeved shirts pointless.
- northrend worgen's arm spikes.
- plate and cloth eyepatches. If not look-a-likes for the leather/mail versions, the cloth one could be a blindfold to cover just one eye and the plate one could be bolted on (like Odin in the Marvel movies).
- more pirate hats, especially leather. Like a tricorner, and a bandana worn like a pirate scarf.
- Northrend worgen face mask.
- Antlers. Previously, the antler helmets all had the antlers attached to some other hat or sweatband, but there should be a model with them growing directly out of the head. For Tauren, moonkin, and stag models, they should replace the existing horns/antlers.
- more voodoo masks, especially mail.
kilts, stopping at the knee. They wouldn't all need to be plaid, there are troll npcs with tribal kilts already. But for plaids, there could be an assortment, like Bronzebeard, Wildhammer (royal), Wildhammer (Kirthaven green and gold), Dark Iron, Wrynn, Gnomeregan.
shoulder:
- northrend worgen monion.
- Johana's shoulders from HotS
geta, tall enough that the player model would have to be elevated above the ground a few inches.
back:
asymmetric tattered cloak (long).