Some of the obvious things I have used them for recently is in soap and other body products. I use some for when we are sick as an inhalation therapy in a bowl of hot water with a towel over our head or a couple drops on the shower floor before a hot shower. Same goes with the bath for sickness or just relaxation reasons. I just read somewhere that you should always follow the dosing recommendations though, even in a bath full of alot of water, because they do not dilute and stronger doses may not be safe, depending on the oil. There is a wealth of information at http://www.aromaweb.com/essentialoils/default.asp that defines each oil by common name and gives information you should not be without, but my favorite resource is http://www.100pureessentialoils.com/pages/properties-uses.html because they give the properties and, if you are looking for scent information and are lost as to what to mix with what, they have a top, middle, and base note info for each scent. No reason to waste your precious oils competing with each other or getting lost under a super strong one. They also list common illnesses and the appropriate oils to use for aromatherapy or other ways. Please read as much as you can before using them for safety reasons.
That being said, when you go to purchase them, you will have many options including organic. It is a good option because you do not want pesticides getting a free ride into your system. Quality varies with the company and some do dilute their product. Again, read up! This has been a really fun part of making my own products. I am saving up for a particularly expensive one that knocked my socks off at the local organic market last week for use as a perfume. Make sure you smell them at places like this before you buy for soap or body products unless you need it for therapy reasons and have to get what you have to get... just sayin. Its also a great place to find out what all those mysterious ones really are like.
You will also find that there are mixtures of oils already put out there for relaxation/nervous tension, alertness/focus, or other mood changers. Just do a quick read at one of the sites above to know properties they have, you may find they may not be the great mix you thought or they are even better than purchasing them separately. Have fun!