Ray-casting on Graphics Processing Units (GPUs) opens new possibilities for molecular visualization. We used this technique to develop HyperBalls, an improved ball & stick representation replacing tubes linking the atom spheres by hyperboloids that can smoothly connect them. This type of depiction is particularly useful to represent dynamic phenomena and can routinely, accurately and interactively render huge macromolecular assemblies with more than 500,000 particles. Combined with Molecular Dynamics (MD) software and haptic devices, it is possible to manipulate molecular objects to study their properties.