A "Consumer Grid" provides the individual-based counterpart to the organisation-based computational Grid. We describe a Peer-to-Peer system for utilising computational resources on the Grid - extending existing work undertaken in systems such as Entropia and SETI@home. The potential of such a distributed computing resource has been in some ways demonstrated recently by the SETI@home project, having used over 650,000 years of CPU time at the time of writing. A user develops applications within such an environment using a visual workflow system called "Triana" - which automatically generates suitable code for distribution, and can support the user in making placement decisions for their modules. Triana will also be deployed as the workflow enactment engine along with the Grid Application Toolkit (GAT) within the European GridLab project.