The use of の
Apart from being the equivalent of the genitive, are there other uses for the particle の?

Question

Answer

One major other use of の I know is in sentence endings.

1) かれは そう いった
2) かれは そう いったのだ。
3) かれは そう いったんだ。

#1 is direct and plain. 
のだ in #2 makes the sentence smoother, giving it a feel of a statement, like "It is that...".

This のだ is as often as not abbreviated to んだ as in #3.
You see these forms all over the place in Japanese texts.