For Natural:
New levels of weapons customization, some weapons moved from unlockables to selectable, scabbards / sheathes, backpacks of multiple forms, arm/leg pouches, new helmets, a few more moustache / beard choices, and as was mentioned above, some more historical / pseudo-historical outfits, like an 18th century military uniform (a la Nemesis), more steampunk stuff including new goggles, an Aviator's Cap (the early 20th century leather flying caps). Upper arm bands, Upper leg (thigh) bands, Split skirts (front narrow hanging strip and another in back), Improved texturing choice for skin on the female allowing more muscle. Improved sliders (general) allowing more bulk / muscle for the female avatar (a la She Hulk (among others) in mainstream comics. New animations showing a sword being put away IN a worn scabbard/sheath costume piece. For the Cowboy / Western end: Chaps Pants, for male and female. Spurs for boots, New trenchcoat options. A general-use "buttcape" based on the Widow's, but colorable / patternable. Worn furs for barbarians / cave-people. A head morph that allows one to look Neanderthal. Heavy aviator's leather (with fleece) jacket / bomber jacket, with back marking, either a default "blood chit" from WW2 or replaceable with a logo (including your SG logo). Aviator's fleece-lined leather gloves. REALLY flared-out pants a la Nazi pants (also used by Pre-WW2 aviators, thus not solely limited to that specific instance). World War 1 helmets, including British "dough boy" type and German "spike" helmets. Modern tactical gear like vest-only flak/kevlar, preferably with lots of optional "chest detail" add-ons like grenades, magazines, etc. Night Vision Goggles as a head detail, both the older bulky ones and the more modern flip-down types.
For Mutant
Redone beastial heads (morphable using the face sliders), new ones based on "normal" animals, such as a fox/wolf (one head, differing coloration), rodent (generic handling rabbit, squirrel, and mouse), bird, and insect with mandibles (mentioned earlier). Tentacles REPLACING arms (left, right, both, like in the Robot Arm choice normally), back tentacles, a third arm (from chest or back or in place of a tail). New tails, most notably a fox/wolf one (again simply a matter of one model and two colors). HAIR that can be put effectively on the beast heads (this kind of thing HAS been seen in mainstream comics in the past). Improved modeling of the existing digitigrade legs, maybe also with more options including better / denser fur, new digitigrade feet, and new feet / boots including the aforementioned birds' feet (also usable for bats). A back-piece (as mentioned earlier using the Bane Spider animations) with either insect legs or tentacles, all cosmetic, nothing more. Lastly in this, an effective snake / cobra head, possibly based around or even ripped from the CoV Snakes. A snake body replacing the lower legs (again using the existing Snake work). A centipede body (same as previously mentioned Snake, just different texturing / animations, and legs that are "invisible" (alpha'd out) in snake form. New forms of spikes / body projections, especially ones for crystals poking through shoulders, arms, legs, etc. Mineral / faceted body, possibly translucent / see-through. Organic weapons REPLACING Gloves / Hands. EYEBALLS. As in eyeballs as shoulder pieces, an eyeball on your chest, eyeball gloves (with flesh option and glove options) so the back of the hand has a moving eyeball. Re-done glossy / rainbow/oil-hued chitin armor / insect armor. Someone mentioned the Coralax above, and I think this, too, would be an excellent addition, since you can already get it as a Halloween costume.
