Do Ngoc Diep:

A survey of noncommutative geometry  methods for Group Algebras

Journal of Lie Theory, vol. 3 (2), p.149-176

In this survey we shall report about a K-theoretic approach to study group 
algebras. Following the example of the group of affine transformations of the 
straight line, the method consists of: 1. Construction of irreducible group 
representations (orbit method, category ${\cal O}$), 2. Decomposition of the 
group algebra into a sequence of repeated extensions, and finally 
3. Computation of the extension
invariants by the methods from noncommutative geometry (KK-theory, 
cyclic theories).