Despite over a century's study, the trigger mechanisms of cardiac arrhythmias are poorly understood. Modern experimental methods do not provide sufficient temporal and spacial resolution to trace the development of fibrillation in samples of cardiac tissue, not to mention the heart in vivo. Computer simulations of electrical activity in cardiac tissue offer increasingly detailed insight into these phenomena, providing a view of cellular-level activity on the scale of whole heart chambers (atria or ventricles). Already, advances in this field have led to developments in our understanding of heart fibrillation and sudden cardiac death and their impact is expected to increase significantly as we approach the ultimate goal of whole-heart modelling. This paper presents a roadmap for the development of Beatbox; a computer simulation environment for computational biology of the heart-an adaptable and extensible framework with which high performance computing may be harnessed by researchers.