Nonlinear holography deals with the realization of dynamical phase gratings inside nonlinear media. In our group we develop devices specifically aimed at realizing dynamical holograms at different laser wavelengths and working with low powers. The realized devices allow us to setup optical experiments where two or more beams interact inside the medium. The results demonstrate the great potential of application of the nonlinear holography techniques. Among them, we can cite the slow-light effect with which we are able to decelerate light pulses down to group velocities as low as meter/second, the phase-conjugation, which realizes efficient corrections of wavefront aberrations, the adaptive interferometers, which provides detection of displacements as small as fractions of picometers.