In X-ray binaries, neutron stars (the very dense stellar remnants of heavy stars) accrete matter from a close-by companion star. This matter eventually falls on the neutron star, significantly affecting it. I.e., the star is spun up to very high spin rates. In the end, it might rotate 1000 times a second which causes very fast oscillations in its X-ray brightness. This workshop was to celebrate the 10th anniversary of the discovery of the first system in which this signal was found and discuss the most recent observational and theoretical insight in the nature of these systems.