  Ultra-high-energy neutrinos and cosmic rays produce short radio flashes
through the Askaryan effect when they impact on the Moon. Earthbound radio
telescopes can search the Lunar surface for these signals. A new generation of
low- frequency, digital radio arrays, spearheaded by LOFAR, will allow for
searches with unprecedented sensitivity. In the first stage of the NuMoon
project, low-frequency observations were carried out with the Westerbork
Synthesis Radio Telescope, leading to the most stringent limit on the cosmic
neutrino flux above 10$^{23}$ eV. With LOFAR we will be able to reach a
sensitivity of over an order of magnitude better and to decrease the threshold
energy.
