This paper is a summary of experimental results obtained on spin-dependent transmission of hot electrons through thin ferromagnetic films. The goal of this contribution is to demonstrate that very simple devices can be used for measuring the spin polarization of a free electron beam. Both cases of free-standing magnetic metal foils and ferromagnetic metal/semiconductor Schottky diode are studied here and analyzed in terms of electron spin detection. In these experiments an electron beam is injected from vacuum into the magnetic thin film with controlled energy and spin polarization. The spin-dependence of the transmitted current, originating from the spin-filtering through the magnetic layer, yields a new and efficient way for measuring the incident electron beam polarization.