Potential applications of cloning go well beyond the popularly envisioned replication of valuable animals. This is because targeted genetic modifications can be made in donor cells before nuclear transfer. Applications that are currently being pursued include therapeutic protein production in the milk and blood of transgenic cloned animals, the use of cells, tissues and organs from gene-modified animals for transplantation into humans and genetically modified livestock that produce healthier and safer products in an environmentally friendly manner. Commercial and social acceptance of one or more of these early cloning applications will lead to yet unimagined applications of nuclear transfer technology. The present paper summarises progress on three additional applications of nuclear transfer, namely the development of male livestock that produce single-sex sperm, the transfer of immune responses from animals to their clones to permit the production of unlimited supplies of unique polyclonal antibodies, and the generation of genetically modified animals that accurately mimic human diseases for the purpose of developing new therapies. However, the myriad applications of cloning will require appropriate safeguards to ensure safe, humane and responsible outcomes of the technology.