I believe there is one other. According to the Bible, Heaven, Hell, Angels, Demons, and God Himself dwell in the 'Eternal Places', speaking of the Spiritual Dimension (Dimension, world, realm, plane,whatever).
And Doguga I completely agree with what you say, and here's why:
Meditating is done to bring you to new and higher levels of consciousness and/or peace.
The reason this is relevant is because by meditating and focusing on what you cannot see around you through various concentration methods used in social castes around the world for thousands of years, you are aligning your soul with your spirit.
By aligning your soul with your spirit, you are becoming more in tune with the spiritual dimension and thus becoming aware of what is happening around you in it. This method is used on some small scale every time a christian prays, and the closer to God and better and this the christian is, the better he/she can connect to the spiritual realm.
I mentioned the soul and spirit a second ago...
The difference is that your soul governs your mind, emotions, and will, while your spirit is the part of you that is connected to the spiritual realm, the breath of God in you.
Your mind is your logical aspect, governing logical thought patterns, book smarts, and pretty much common sense based on the experiences you hear, see, feel, taste, and touch around you.
Your emotions of course govern..well..your emotions (not sure how to say it). The change in mood caused by events or things taking place around you.
Your will is a very special part of you, because your will is the one area that is completely off limits to spiritual beings. God says that he has granted us free will, and He respects that without exception. Demons cannot force you to do something, and neither can angels, and God refuses to.
When you concentrate/meditate, and the more often you do it, you will be able to get closer to the spiritual dimension. This can be both good and bad. If you're not in the right place, then it can be bad, because this opens you up to ALL of the spiritual dimension. This means that demons can better attack you when you do this, if you are not in a spiritually sound position.
I believe this is the main reason the Bible warns against mind affecting herbs and substances. For example, when you smoke weed, you are opening yourself up in a slow and subtle manner for demonic attack because you are both crippling your ability to think at the same time that you are opening up to the spiritual dimension. This usually leaves you open for harmful demonic attacks because they are hostile, while God is a perfect gentleman and he won't invade your thoughts and consciousness without your consent.
That's a few of my thoughts on the spiritual dimension.