Service grid is an infrastructure for service-oriented collective intelligence. It provides a set of enabling functionalities to support coordination of services, such as service registries, service composition, access control, and monitoring. To form the service-oriented collective intelligence, various types of services need to be connected on the service grid, and managed by the service grid operator. However, it is difficult for single service grid operator to gather and organize services in various domains. Therefore, building service grids in different domains and connecting these service grids are essential for expanding service-oriented collective intelligence across domains. To this end, we have designed a service domain model to specialize general-purpose service grid to a specific domain and realize interoperability among service grids. Moreover, we have also developed service grid federation architecture to share service registries, compose services across service grids, and control and monitor accesses to the composite services. Finally, we have applied the proposed architecture to the language service domain to construct the Language Grid.