The quality of lipid bilayer simulations has been quite extensively evaluated under various conditions, -100 yet determining unambiguously the overall accuracies of different force fields remains still unclear, as exemplified in Table . Within the NMRlipids Project (nmrlipids.blogspot.fi), we have used the open collaboration approach, inspired by the Polymath Project 101 and open-source software development, to find lipid force fields that would correctly capture the lipid conformational ensembles and ion binding to membranes. So far, we have used the data collected through the open collaboration to evaluate against NMR data the lipid headgroup conformational ensembles and ion binding affinities to membranes in the most commonly used force fields, and to propose the inverse conformational selection model for lipid-protein interactions. We are currently us- ulation trajectory qualities against NMR and X-ray scattering data, and enable arbitrary user-defined automatic analyses over the vast sets of MD simulation data.