In the article, a new approach is proposed to personalize mass-scale information systems. The approach is based on the technology of software agents, and the Agent Computing Environment ACE. The ACE agents are programmed and managed by the end-users. Basic tasks of an agent are related with efficient, individualized access and monitoring of selected information sources. Once developed and moved to given location, an agent performs autonomously given tasks, pre-programmed according to its owner's needs. Each ACE agent may adjust its behavior to the environment where it is executed at a moment, as well as to some user-independent restrictions, e.g., communication costs, limitations of end-user hardware, etc. Several agents may be logically combined to create a complex agent able to fulfill more sophisticated tasks. Complex agents may be settled both statically, as a result of a user request, and dynamically, as a result of environmental changes.

The approach may be used in such domains, as: e-banking, sport and cultural news, health and telemedicine, shopping and e-commerce, logistics, e-learning, etc. Using ACE agents as external brokers to distributed systems makes it possible to personalize behavior of such closed and highly secured environments as bank databases, company's internal systems, etc.