I also use oils on my hair rather than use styling smoothers. The essential oils like tea tree, peppermint and herbal extracts are great for smoothing hair after or before straightening. It helps keep those "fly aways" down. Be sure not to use the tropical extracts like citrus (lemon, lime, orange etc) because those are a bit acidic and can harm your hair.
Medicinally the minty oils like eucalyptus are great in your humidifier to help with congestion. It's much better than using petroleum products that use that same extract. It doesn't take much to get into your system. Sniff them right out of the bottle, they work amazingly well. Lavender oils are great for helping you get to sleep, a few drops in your bath and you will be ready for a nap or bed time. The citrus oils are great for waking you up, a bit of citrus oil in the morning after a shower is invigorating. Floral oils are a great replacement for those toxic perfumes made from chemicals.
I have only touched on some of the uses for essential oils. There are some wonderful sellers, like I mentioned above. Many of the cosmetic companies are starting to sell them because they know that people are moving in the direction of less toxins and more natural and organic applications.
What do YOU use essential oils for?