The paper describes how the Web can be used as a support for intensive querying and display of large moving objects databases. We present first an architecture for a system which integrates incoming events provided by GPS servers in a spatio-temporal database, and permits to register queries over this database. We focus on continuous queries that allow users to receive notification of events affecting the initial result, and discuss the process of matching queries and events in order to perform this notification. Finally a prototype implementing a simplified version of this architecture is described. It uses standard XML-based languages in order to visualize the result of a query as dynamic maps where the motions can be tracked in real time. General Terms Performance Categories and Subject Descriptors D2 [Software]: Domain-specific architectures