Rich new data sets on galaxy distances, from proper motion measurements of Local Group galaxies to sparse but accurate SNIa measurements at large distances, are leading to increasingly detailed maps of the distribution and motions of galaxies. The distribution of matter in the universe controls the motions of galaxies. Studies of galaxy flows on scales from infall onto groups to streams across 100 Mpc dimensions give information on the distribution of matter otherwise unavailable. Theoretical studies are making use of the observational constraints to infer initial conditions and then use this information to generate simulations that increasingly resemble the universe we live in.
