Acid Blood: You Hurt Me and you get some back. Is fun at times, but the only place that I can see that it would be really useful, is on a carnifex kitted out for close combat (oh wait, you can't), Tervigon (Same.) or a Tyrant kitted out for combat (you can here).
Acid Maw: Yay it's a power weapon.
Adrenal Glands: Furious Charge For Everyone in this book. Though the only ones who should take it are Tervigons, Carnifex w/o crushing claws, and (surprisingly) Gargoyles. Never underestimate that Blinding Venom at Strength 4 and Initiative 5. Especially when combined with a Flyrant Granting them Prefered Enemy. Great Fun.
Blinding Venom: Only comes on Gargoyles and makes any roll to HIT of a 6 and auto wound. AMAZING!
Chameleonic Skin: Great way for Lictors and Death Leapers to arrive.
Containment Spines: In the Weapons
Frag Spines: Frag Grenades
Implant Attack: Another Way To Cause Instant Death, Less reliable and more expensive than boneswords, and comes as an option on mosters that can take boneswords. Just take the boneswords.
Regeneration: A cool ability that lets you re-gain wounds. On most things it is a waste though. Take it on Harpies, and Tyranofex though. They'll benefit the most from it. Tervigons not so much since they will be taking either too many wounds, or not worring about wounds.
Toxic Miasma: a very useful little kicker to melee. not available on too many creatures though. Sure would be nice if you could take this on a carnifex... alas no.
Toxin Sacs: Poison 4+ wooooo. Great on Genestealers, and Tervigons, not much else.
Wings: Poor wording since they will Move As Jump Infantry instead of being jump infantry. too many wording screwups in this book.