Below is just one of four races I've imagined so far. I've did write ups for 2, including the one below and the other two races are unwritten as of yet.
If the spacing and the indenting and all that is all screwed up, I't this message boards fault!! Tell me what you think.

The Tasleen

The Tasleen don't have a home world as we know it. They, instead, have a home asteroid
belt. Long ago, when their solar system was still forming, a very large asteroid with a
high dark matter content exploded for reasons unknown within the proximity of Tasla, the
name of the Tasleen star. The fragments of the asteroid got caught by Tasla's gravity and
became a very dense asteroid belt. The dark matter in the asteroid fragments started
attracting interstellar gas. After a while, the large belt of rock fragments were surrounded
with an atmosphere. The Tasleen call this, Tasla Prime. It is their home. Due to the
gravitational inconsistencies from rock fragment to rock fragment depending on how
much dark matter is contained within it, the atmosphere on Tasla Prime can be much
thicker in some areas, and much thinner in other areas. Tasla Prime is located between
the third and forth planet orbiting Tasla.

Because of the huge differences in atmospheric pressure from area to area, the Tasleen
have developed 2 sets of 2 lungs. The small set of lungs kick in when a Tasleen enters an
area with very thick atmosphere. The large set kicks in when a Tasleen enters an area of
thin atmosphere. The Tasleen have also developed very strong telekinetic abilities to help
them cope with the sometimes massive fluctuations in gravity whenever they "rock hop,"
as the Humans call it, from asteroid to asteroid. Sense they use telekinesis to travel, the Tasleen do not have legs. The Tasleen do however have webbed arms, similar to that of a
flying squirrel, to help them glide through the air. The facial features of a typical Tasleen
are very few. Like Humans, they have 2 eyes and 1 mouth, but they do not have a nose to
speak of and they have 4 ears. Their craniums flow down their back much like a Human
female's hair would, and it reaches down to about half the length of a Tasleen's body.
Rather than a their craniums be rigid and bony, their craniums are made up of a thick
layer of cartilage. This makes their craniums flexible to a degree. The Tasleen
communicate via combinations of howling at different frequencies and pitches. Another
feature the they have is that they have bluish-green skin. However, the exact shade
varies between individuals. Some Tasleen can have skin that is completely blue, or
completely green. Another thing about the Tasleen is that they are marsupials. After the
birth of a young and small Tasleen, it is carried by the male in a small pouch untill the
baby Tasleen is big enough to crawl out and move around on it's own.

The Tasleen have a republic form of government. 300 senators meet at the Tasleen's
capital city to discuss internal affairs. The senate has a primary senator who controls the
Tasleen military forces with the aid of several military advisors. He/she cannot send
military forces into a war or battle without the majority vote from the rest of the senate.
The Tasleen goes through its peaceful and aggressive eras. It usually depends on the
general attitude amongst the Senate and the people it governs at any given point in time.

Tasla Prime is described as quite a beautiful place by the non-Tasleen who have been
there. The sky is a purple-blue color and many of the asteroids have a very soft moss
growing on them. This moss is Talsa Prime's equivalent to grass on Earth. There are several
indigenous animal and plant life forms on Talsa Prime, but the quantity and diversity of
life on Talsa Prime is microscopic compared to that of Earth's. A typical city on Talsa
Prime could cover several asteroids. The buildings on Talsa are wide and tall. Some
smaller asteroids on Talsa prime are completely covered, from pole to pole, by a single,
curved building. Large structures on Tasla Prime aren't equipped with stairs or elevators
sense the Tasleen can just as easily fly toward whatever floor they need to be on. A
popular material for buildings on Tasla Priem is hard grey-white material that is reminiscent of
marble only it is much, much stronger. The Tasleen are also very fond of observatory
domes and great outside views. The result is that many Tasleen structures would either
have observation domes or tall towers with many large observation windows at the top of
them.

An animal species on Earth known as "rods" actually originated on Tasla Prime. The
rods were introduced to Earth's environment in the Earth year 1897 when an exploratory
vessel filled with them crashed on Earth. The occupants of that vessel were rescued, but
the extremely adaptable rods could not be recaptured and they were left on Earth. This
fact is not widely known amongst Humans.

[ December 03, 2001: Message edited by: MIB ]

I do like the lung bit - neat. However, I can't quite visualise the cranium part . . . perhaps a picture?

All in all a good start - an excellent rough draft - you've obviously put a good deal of thought into this. I look forward to a more detailed version.

*pulls out SW Encyclopedia*