Improve the readme.

README.md

@@ -4,9 +4,30 @@ nalgebra
 **nalgebra** is a _n_-dimensional linear algebra library written with the rust
 programming language.
 
+## Features
+**nalgebra** is meant to be a general-purpose linear algebra library (but is very far from that…),
+and keeps an optimized set of tools for computational graphics and physics. Those features include:
 
-It is mainly focused on features needed for real-time physics. It should be
+    * Vectors with static size: `Vec0`, `Vec1`, `Vec2`, ..., `Vec6`.
-usable for graphics too.
+    * Square matrices with static size: `Mat1`, `Mat2`, ..., `Mat6 `.
+    * Dynamically sized vector: `DVec`.
+    * Dynamically sized matrix: `DMat`.
+    * Geometry-specific matrix wrapper: `Rotmat`, `Transform`.
+    * Most well-known geometric functions.
+    * A few methods for data analysis: `Cov` (covariance), `Mean` (mean).
+    * Operator overloading using the double trait dispatch [trick](http://smallcultfollowing.com/babysteps/blog/2012/10/04/refining-traits-slash-impls/).
+    This allows using operators for both matrix/matrix multiplication and matrix/vector
+    multiplication for example.
+    * Almost one trait per functionality. This is very useful for generic programming.
+
+Since there is almost one trait per functionality, one might end up importing a lot of traits. To
+lighten your `use` prelude, all trait are re-exported by the `nalgebra::vec` and `nalgebra::mat`
+modules. Thus, to bring every functionalities of `nalgebra` in scope, you can do:
+
+```rust
+use nalgebra::vec::*;
+use nalgebra::mat::*;
+```
 
 ## Compilation
 You will need the last rust compiler from the master branch.
@@ -16,7 +37,19 @@ If you encounter problems, make sure you have the last version before creating a
     cd nalgebra
     make
 
+There is also a light, but existing, documentation for most functionalities. Use `make doc` to
+generate it on the `doc` folder.
+
+## nalgebra in use
+
+    * [nphysics](https://github.com/sebcrozet/nphysics): a real-time physics engine.
+    * [ncollide](https://github.com/sebcrozet/ncollide): a collision detection library.
+    * [kiss3d](https://github.com/sebcrozet/kiss3d): a minimalistic graphics engine.
+
+Feel free to add your project to this list if you happen to use **nalgebra**!
+
 ## Design note
+
 **nalgebra** is mostly written with non-idiomatic rust code. This is mostly because of limitations
 of the trait system not allowing (easy) multiple overloading. Those overloading problems ares
 worked around by this