In this paper we discuss the development of metamaterials containing ferromagnetic microwires which makes it possible to tune the electromagnetic response in the microwave frequency band. Metallic wire media are known to demonstrate very strong dispersion of the effective permittivity at GHz frequencies. At certain conditions, the magnetic properties of constituent wires may strongly contribute to the system losses owing to the magnetoimpedance effect, resulting in unusual dependence of the permittivity on the external magnetic or mechanical stimuli. We also demonstrate the possibility to design the wire media with a negative index of refraction utilizing natural magnetic properties of wires. The results involve theoretical modeling and measurements of the reflection/transmission spectra by free-space methods. A reasonable agreement between theoretical and experimental data is demonstrated.