We present a synthesis of the different numerical methods developed these last few years in the laboratory to solve frictional unilateral contact problems. The classical variational formulations associated to the static case are extended to complex quasi-static loading cases by the use of velocity terms in the formulations. A generalization for viscoelasticity and viscoplasticity is given. Contact is dealt with by the use of different numerical methods relaxation with projection, mathematical programming, improving the fixed point on boundary conditions through penalization. Techniques for algorithms are presented. Their efficiency is discussed on test examples and applications concerning industrial problems are presented.