Galaxy clusters are the most massive gravitationally bound objects in the universe and, as such, are extensively used as cosmological probes. These systems are usually assumed to be relaxed & spherical to simplify the analyses. High angular resolution X-ray and, now, Sunyaev-Zeldovich Effect (SZE) measurements often reveal striking deviations from equilibrium. These signatures convey information about the physical processes in, and history of, the Intra-Cluster Medium, and can bias and degrade results from large scale SZE surveys. The GBT is now engaged in a systematic survey of SZ clusters at high angular resolution using MUSTANG. I will present results from this ongoing campaign, describe our plans for further observations, and discuss future directions. I will also present a brief overview of the range of 3mm science programs currently ongoing at the GBT, and of development plans.