Like pretty much any other creature, elementals can be enhanced by using mutations. Here are some ideas for each type of elemental:
All elementals:
Chemical Gland and Alter Atomic Composition represent how the elemental can take existing (periodic) elements in the environment and recombine them or create new ones. An earth elemental with chemical gland can remove salt from the ground and use it as a blinding spray attack or turn iron weapons and armor it hits into lead or gold. A water elemental can break water up into hydrogen and oxygen and use them as a flamethrower or it could turn alcohol into mercury and use it as a powerful poison. A fire elemental could create patterns of color in its flames by burning different materials created from the air and soil or it could burn much hotter by turning iron into phosphorus and feeding on it. Air elementals could use nitrogen and carbon in the air to make explosives that will detonate when ignited (say from a torch), turn nitrogen into neon and cause the air to glow in wierd ways when exposed to electrical attacks or turn oxygen into any gas and suffocate living creatures. Spirit or Quintessence elementals usually don't have physical mutations. They may have Alter Atomic Composition as a psionic power and if so, typically use it to turn solids or liquids into ectoplasm.
Quickness is a natural for fire elementals (which should have a much faster movement rate) but can also apply to the others. Even earth elementals can be made up of light minerals and metals.
Control Light Waves is a natural for air and fire elementals. For earth elementals, it is used by those with bodies made up of transparent or translucent gemstones.
Control Sound Waves (renamed Bend Sound from Creatures of the Wastelands) can be found in all of them except spirit elementals. They can make themselves silent or increase the sounds they make enough to stun or even cause damage.
Earth elementals:
Gravity Control may seem odd at first, but gravity is based on mass and earth elementals exemplify mass. It allows the elemental to draw creatures and objects to it (20 pounds per hit die). This is an area of effect mutation and the elemental can turn it off and on, but not give it direction.
Warp Form (new) is a nasty ability to treat solids as if they were clay. An earth elemental with this power could easily destroy weapons and armor as well as warp people and creatures, doing them dexterity and strength drain.
Fire elementals:
Energy Ray (cold, variant) is the last thing that most people who expect from a fire elemental. Yet is sort of makes sense if you consider they control energy rather than just flames. They heal themselves by draining heat from their environment. In effect they have fast healing 1 and when they use their ray, they heal 1/2 of the damage they inflict.
Energy Ray (heat, variant) is a shared ability with water and air elementals. Instead of cooking the target, the damage is the result of dehydrating it. Obviously it only applies to creatures and objects with some water content.
Water elementals:
Where earth elementals are all about mass, water elementals have abilities based on density. Some of them have one or both of the Density Alteration mutations (self and other). But these powers are much more advanced than the mutations. They can increase or decrease the density of an object without altering its volume. This means objects that in effect become incorporeal or super heavy (consider a set of armor that weights 10 tons). They could also decrease the density of a surface, such as a wall or floor, and create pits that are impossible to detect until someone falls in. If someone is within such a pit or in water, the elemental could then increase the density and encase the victim. An amber like attack as it were.
Adhesion Control (new) is the result of how water causes things to stick to each other. It isn't a powerful effect on the human scale but it does allow insects and other small animals to walk on water. Under the control of a water elemental, a wet victim could be glued to all his gear, in effect causing dexterity damage. Worse it could be used to suffocate someone by gluing their mouth and nose shut.
Air elementals:
There isn't much about gasses that one could use for a mutation like power beyond what I wrote above. Inflicting cold damage by decreasing their own density, snuffing or redirecting fire and creating a dust or sand storm are all that I could think of. Have any suggestions?
Spirit elementals:
As these are astral based psionic beings, spirit elementals can have mental mutations. Empathy, Possession and Plane Shift are the most insideous attacks among the mutations found in the MF core book. With Empathy, the elemental can manipulate a group into disliking or even attacking each other, Possession makes this even easier and Plane Shift can send one or more members into whatever plane the elemental wants (just form the portal under them).
