Peppermint, Mentha piperita: Useful in treating headaches, muscle aches, digestive disorders such as slow digestion, indigestion, and flatulence.
  For more information please read Peppermint, Mentha piperita by Dennis Willmont

Eucalyptus, Eucalyptus globulus or Eucalyptus radiata: Helpful in treating respiratory problems, such as coughs, colds, and asthma. Also helps to boost the immune system, and relieve muscle tension.
  For more information please read Eucalyptus, Eucalyptus globulus by Dennis Willmont

Ylang Ylang, Cananga odorata: Helps one to relax, and can reduce muscle tension. Good antidepressant.

Geranium, Pelargonium graveolens: Helps to balance hormones in women, good for balancing the skin. Can be both relaxing and uplifting, as well as antidepressant.

Lavender, Lavandula angustifolia: Relaxing, and also useful in treating wounds, burns, and skin care.

Lemon, Citrus limon: Very uplifting, yet relaxing. Helpful in treating wounds, infections, and house cleaning and deodorizing.

Clary Sage, Salvia sclarea: Natural pain killer, helpful in treating muscular aches and pains. Very relaxing, and can help with insomnia. Also very helpful in balancing hormones.

Tea Tree, Melaleuca alternifolia: A natural anti fungal oil, good for treating all sorts of fungal infections including vaginal yeast infections, jock itch, athletes foot, and ringworm. Also helps to boost the immune system.

Roman Chamomile, Anthemus nobilis: Very relaxing, and can help with sleeplessness and anxiety. Also good for muscle aches and tension. Useful in treating wounds and infection.

Rosemary, Rosmarinus officinalis: Very stimulating and uplifting, good to help mental stimulation as well as to stimulate the immune system. Very good for muscle aches and tension. Stimulating to the digestive system.