Grid Computing is a distributed computing technology that can provide users with powerful computing and storage capacity. Most of the applications of grid computing are now replaced by the use of cloud computing. However, there is an area where the grid computing technology can still be utilized, that is in the area of desktop grid computing (DGC). With the growth of desktop computer belonging to an organization and the increasing of internet penetration worldwide, desktop grid computing can be a good alternative to provide the cheapest high-power computing to solve computing intensive applications by utilizing non-dedicated resources. DGC can also be utilized if an application involved some sensitive and secured data. Another area where DGC can be useful is to support the concept of volunteer computing which is expected be more popular in the future since devices that can be volunteered are not only limited to desktop computers but also other computing devices such as smart phones. The main objective of this paper is to review some available middlewares for DGC. This paper also discusses the future direction of DGC.