A very unique, misunderstood, and oft-criticized "LDS-ism" is the concept of Kolob. I really can't classify Kolob as a doctrine because It is rather obscure. And it is unfortunate that critics of the LDS Church tend to put so much focus on this rather obscure detail because in reality, the concept is teaching something really very simple yet very profound.
The concept of Kolob is found in the Pearl of Great Price. The Pearl of Great Price contains a variety of translated scripture and history by Joseph Smith. The part the mentions Kolob comes from the Book of Abraham which Joseph Smith translated from Ancient Egyptian papyrus that came into his possession. Using a "Seer Stone" or "Urim and Thummin" like what Aaron the High Priest possessed in the Bible, Joseph Smith was able to translate the Book of Mormon from discovered Golden Plates as well as other ancient documents which can now be found in the Pearl of Great Price.
The original papyri collection containing the Abraham scroll was partially destroyed in the 1871 Great Chicago Fire. Some fragments of the collection have since been discovered. Excepts from the surviving fragment all come from the well known Egyptian funerary texts, "Book of the Dead" and "Book of Breathings". The Abraham scroll, unfortunately, is not among the known surviving documents. Joseph Smith's notes describe the dimensions of the Abraham scroll and these details do not match the dimensions of the surviving papyri.
Kolob is a concept briefly described in the Book of Abraham in the Pearl of Great Price. There is also an LDS Hymn entitled "If You Could Hei to Kolob". Kolob is described as a celestial governing sphere near the throne of God. What that means to be "near the throne of God" I don't know. The Lord does not tell Abraham that Kolob is at the "center of the universe" or that the Universe even has a "center". Also, the Book of Abraham does not say God lives on a planet called Kolob. What it says is that Kolob is "near" to God. Again, what it means to be "near" I have no clue. This is speaking figuratively so anyone making concrete claims about this is very mistaken and should be more responsible with their criticisms.
What God is telling Abraham is that He is a God of order and accordingly, the Universe (which is God's creation) manifests order and structure and a hierarchy. Understanding the order and structure of the Universe is important because we see the same order, structure and hierarchy in God's kingdom and Church on the Earth.
Unfortunately, in reaction against the Catholic Church, denominational and non-denominational Christian churches reject the concept of structure, and hierarchy in Christ's Kingdom. The mainstream Christian concept of the Church is very similar to science's concept of the Universe which is that galaxies like individual congregations are just out there independently and homogeneously doing the same thing without any guiding super-structure.
What I mean is that unlike the Primitive Christian Church with a Chief Apostle Peter and 12 Apostles, and Seventies like Stephen who served to oversee and establish the local Bishops and congregations, most Christian Churches believe that their is no earthly authority higher than the pastor or bishop of each individual congregation.
In Cosmology, this is like saying there is no structure above an individual galaxy. However, science has known for a long time that our own galaxy is at the center of a group of 54 galaxies and dwarf galaxies known as the "Local Group". And the "Local Group" itself is part of an even larger organization known as the "Virgo Supercluster". Then on top of that we have voids and filaments.
Now cosmology is telling us that they are seeing an even bigger structure in the Universe that contains seventy-three quasars, and is over four billion light-years across. This discovery is throwing much of what science thought it knew about cosmology on its head. Not that we know much realizing that with dark matter and dark energy we can only see less than 4% of what we can see.
It is my opinion that God taught Abraham about Kolob and about the structure of the Universe to teach him that God's Kingdom on Earth like the Universe has structure and a well-ordered hierarchy. As opposed to recent and now disproven theories, the Universe is not "homogenous" with random galaxies independently doing the same thing without direction. Rather, just like the Kingdom of God on the Earth, science is just now discovering that the Universe has a guiding super-structure that influences the mechanics of individual galaxies, stars, and planets.
http://www.lds.org/scriptures/pgp/abr/3?lang=eng (Abraham Chapter 3)