This paper concerns the development of interfaces which perform tasks on behalf of the user. Recently the concept of task delegation has gained consideration due to the increasing number of assignments that are quite repetitive and tedious, like dealing with electronic messages, managing personal agendas, retrieving data and information in remote and distributed repositories. These tasks are generally connected to the development of computer networks. The design of such interfaces presents a high degree of complexity, since the relationship with the user and his needs is very critical: in most cases the user wants to control the jobs to be mechanized but in the same time he wants to be free from wasting his time in performing repetitive patterns of actions. In this paper the main problems concerning the design of active and cooperative interfaces are investigated. Then a solution is proposed based on the approaches of software agents and distributed architectures. Starting point of the project is to integrate and make accessible different tools and applications regularly utilized by a user: all these elements concur in building a flexible and scalable environment that the user can access through intelligent agents that work as interfaces.