Abstract: Sterile neutrinos are usually introduced to explain the masses of active neutrinos. If one of these fermions has mass of several keV, it can also account for the cosmological dark matter. The same particle can explain the observed velocities of pulsars, speed up the formation of the first stars and stir up supernova explosions. I will describe a mechanism for sterile neutrino production that involves a minimal extension of the Higgs sector by a gauge-singlet scalar. The relic abundance of sterile neutrinos is produced from decays of the singlet Higgs and does not depend on their mixing angle. The resulting dark matter is colder than the warm dark matter produced in neutrino oscillations. I will discuss the small-scale structure formation properties of these neutrinos and show that they comply with current observations. The presence of the gauge singlet in the Higgs sector has important implications for the electroweak phase transition, baryogenesis, and the upcoming experiments at the LHC.