I havent made a realistic character before.
So now I want to make an armature that will be used for ALL of my characters (for current project).
As they are going to be realistic, I would like to know if there are accurate measures for the lenghts of each bone (joint), such as feet and arms, etc. which i could use when making my humanoid armature
i hope that was clear enough
Welcome to BA.
You make the armature based on your character and the model should have realistic proportions in the first place.
At least my rigs usually consist of 2 parts, a deformation skeletion and a functional skeleton so that it is easy to incorporate changes.
Also the deformational skeleton does not match a human skeleton, especially when it comes to knees, shoulders and hips.
The functional skeleton holds all the limits and constraints more less puppeteering the deformational skeleton.
And a biped rig isn´t that rigid usually, it should be easy to fit it to any character, as you obviously plan.
If you plan on doing a human skeleton based rig and then just create a character around it, you´r most likely about to fail.
well if you put it that way…
Where can i find accurate measurments of human body part lenghts?
Well, thats the art part =)
Learning a sense for proportion and to know anatomy, at leat for realistic organic models like humans, animals and stuff like that, for stylized characters like e.g. Pixar does it doesn´t matter that much, but I guess that is not what you are after.
I recommend to get some art and anatomy books, or just work by reference for particular characters.
3d.sk offers some great free resources many used to start organic modeling.
Else I´d start here and familiarize myself with the basics, like Head to torso ration, leg to head ratio, shoulder to hip ratios and how they influence the appearence, differences is male and female skeleton and proportions.
It is a tough area of expertise to start out with, many consider realistic human modeling the ultimate challenge 
But you can use the forum search for topology and proportion, and look everywhere, that basic knowledge is not limited to blender or 3d software, it is a basis of many arts, from pencil drawning over sculptors, painters, stonemasons, tailors and many more.
I occasionally landed on pages and papers for plastic surgery during my organic modelling research phase =)
Also a nice resource is to look into PHI, the golden ratio =)
And always keep in mind, in realistic organic modeling you hunt to capture the imperfection of organic matter. Perfect organic stuff looks artificial…
You suggest to get a book just for this? Hold on, I didnt mean that realistic. And the models are lowpoly.
What ‘PHI’?
It is not spelled like that. It is pi.
And it is just a reference to the golden mean which is present in many things in nature as well as incorporated into architecture.
That reference link there is great that he gave you. But what you also need to focus on is where the joints of the bones connect.
Here is a great reference for that:
http://www.hippydrome.com/Sketches.html
Just start Googling around and see what you can find.
I found this
mech.utah.edu/ergo/pages/Educational/safety_modules/ctd-anthropometry/index_files/image002.gif
Looks like a direct answer for my question.
The joint connection point location was going to be my next question.
thanks guys
Also, if you guys are using 2.5, can you tell me where i can download the ‘meta rig’, without getting 2.5?
OUCH!
Sorry pal, you fail hard this time =)
Proportions got not much to do with π.
Well a bit, as Pi is the ratio of diameter:circumference of a circle 
Thats a Phi: φ, Ф
And it is (1+sqr(5))*0.5
Better known as the Golden Number, which should be familiar to every artist.
From greek architecture, over italian renaissance it was used over and over again.
And you can find it throughout every second thing in nature, from mussles over various flowers to the proportions of a face.
Faces or Bodies we find attractive usually match the proportions of PHI.
Well cool. I always love to learn something new. I am well read on this subject. But apparently not enough. I was thaught that the the two numbers are very much related. And any study of this you should have encountered the relationship. It makes me wonder where you missed that? My mistake however in not knowing the two symbols and I am far from a mathematician.
http://milan.milanovic.org/math/english/pi/pi.html
But the golden mean, fits into a circle like so:
And I also have been taught that the circle - itself the representation of pi - is also a way to compute many things in nature including the human form:
So my apology for the misspell crit. I was wrong. But I was taught that these two things were more or less interchangeable in theory and practice. Though obviously mathematically and in origin they could be considered worlds apart I suppose if you want to start in on a semantics debate. But I was more or less interested in bolstering (helping to add support) what you were saying. I just thought ignorantly that you had misspelled it.
I do have a book recommendation which puts much of this information into perspective.
In this book he goes into how all of the numbers relate back to the circle. And all geometric forms including the golden mean that artists use and pi itself are arrived from it as well. This is all well documented information from ancient texts on the subject.
So again, thanks for the lesson. 
Cheers.
Fair enough although you don´t need PI anywhere for PHI.
Boiled down you can construct pretty much anything with a triangle and a circle =)
It´s my curse being an engineer and artist. Poets would say I got 2 hearts beating in my chest. Sometimes the artistic obvious escapes me for mathematical or technical reasons and the next day its the other way round =)
You wouldn´t believe how often I got a hard time making something in a movie thats not technically correct because its: not cool, too complicated (no time), not possible…
Interesting situation. I am sure I have similar things going on artistically perhaps in different ways. Well, thanks again for the lesson. I will never mistake pi for phi ever ever again. lol! 
PLEASE someone post the meta-rig in blend 2.49 format?