There is a growing demand for computing power from scientific communities to run large applications and process huge volumes of scientific data. Meanwhile, Distributed Computing Infrastructures (DCIs) for scientific computing continue to diversify. Users can not only select their preferred architectures among Supercomputers, Clusters, Grids, Clouds, Desktop Grids, and more, based on parameters such as performance, reliability, cost, quality of service, or energy efficiency, but can also combine transparently several of these infras-

tructures together. In this chapter we explore several scenarios where Desktop Grids are combined with Clouds and/or Grids to improve performance and quality of service or decrease the cost usage.