The current Web is a mine of tools and services and the gate to ubiquitous computing environments with a huge number of highly distributed mobile and embedded intelligent resources. Their advanced reuse in assistance systems that support whole processes of our tasks requires federation of resources, that is, both discovery of appropriate resources from a certain scope of resources, and their interoperation and coordination for the required demand. Such a scope and the demand may dynamically change. This chapter focuses on such cases in which both change dynamically, and the change of demand cannot be predicted. Assistance systems for such cases must be able to support us to instantaneously perform federation of Web resources in an ad hoc way. They require new technologies for ad hoc federation of Web resources, and for restricting the scope of discovery in accordance with dynamically changing situations. This paper proposes the use of meme media technologies for ad hoc federation of intelligent resources over the Web. It also proposes the Wiki piazza architecture that works as a repository and lookup service, and combines this service with a location reference service to propose a way of restricting the scope of discovery using location-dependent contexts. These technologies enable location-based ad hoc federation of intelligent resources over the Web and ubiquitous computing environments.