Galaxy clusters are the most massive virialized objects in the universe, and have the potential to be highly accurate probes of cosmological parameters. A fundamental challenge for cluster cosmology is to estimate the masses of these objects using observational proxies such as X-ray luminosity and temperature, which are complicated by the merger history of clusters and the microphysical properties of the intracluster medium. These effects, while frustrating to cosmologists, provide a rich laboratory for exploring the plasma physical processes that are occurring in these massive objects. In this talk I will present recent efforts to understand the effects that several plasma processes - including conduction and AGN feedback - have on the observable properties of galaxy clusters.