Gnomes!
Not the stupid garden gnomes, but gnomes like in the Forgotten Realms series or EverQuest. Those are the cool gnomes.
Oh, and telekenesis. I suppose if you were to alter the human body to be able to direct electrical currents, you could hold a metal bar in your hand or something and create a magnet. That's sorta telekenesis.
Oh, and scales. My skin is dry, it's kinda like scales.
Oh, and special antennae made of some material like bone or something elastic, but very durable. And your body could store energy at the base. A tail would work too. And then the body could go into super-energy-burning mode and burn the energy, and channel the energy through a small tube through the tail, superheating it and giving us the ability to hit people with a flaming tail/antenna.
Oh, and for non-human mutations...
Silt Striders (from The Elder Scrolls III: Morrowind). Those would be fun.
And a giant paramecium.
And biological nanobots (Though if a virus is possibly considered not living, then nanobots probably wouldn't either, therefore negating the term biological...)
And creatures that don't expell any liquids at all. All non-consumable waste products (like rocks and plastic and uranium) would be condensed into small compact spheres that can be fired at high velocities at predators. Excess water and other consumables would be stored in vacuoles, and never expelled. As the systems convert water into oxygen and hydrogen and back again, it would created an equillibrium and never have the need to eat or drink again (except in the case of replenishing tissue or growth).
And creatures with the ability to create matter from energy (the opposite of what nuclear power plants do). They could absorb heat from the sun and turn it into nutrients and stuff without the aid of water and other materials.
And creatures that can survive in space. Like a space whale. Orcinus orca celestia. that would be neat. And then we could attach ion beams to shoot at the normal Orcinus orca and make them an extinct species.
I have more but I think this list is getting too long. Bloop!