#3 Lavender

Lavender (Lavandula spp.)

Lavender is my all time favorite essential oil.  It's soothing, clean aroma is pleasant and just inhaling the vapors helps to relax the mind and body.  It's mainly cooling character is also a bit on the dry, astringent side and somewhat bitter.
It's also one of the most popular medicinal herbs since ancient times. The name comes from the Latin lavare, to wash.  Medicinally, L. augustifolia or L. spica are the species used. 
Lavender is one of the safest essential oils and one of only a few that can be applied to the skin neet (straight).
As a relaxant, it's wonderful as a sleep aid. Just place a few drops on a cotton ball near your pillow to encourage sleep.
As a circualtory stimulant and tonic for the nervous system, I've found that placing a dab of lavender EO on my temples and the near the base of my ear (where you'd apply perfume) helps get rid of the odd vision disturbances that accompany migraines.
As an antiseptic, antibacterial and analgesic, lavender is great for wound healing and is used in burn ointments.
It's also helpful for easing sunburn or scalds, eczema, insect bites and stings.
As an antispasmodic, lavender can be added to chest rubs for asthmatic and bronchial spasms and massage oils to help relieve muscle tension.  Because lavender is also an analgesic it can ease muscle pain, too.

But to me, these health benefits are merely extra perks because I simply love the aroma of lavender!