As information available over the Web grows, so does the need for more effective retrieval tools. In this paper we describe three information retrieval agents currently being developed at the National Taiwan University. While each agent serves a different purpose, they share the common feature of incorporating the need of the users. In other words, all three agents offer personalized services. The first agent is an IR agent that utilizes categorical information to assist a user find relevant Web pages. The second one is a website browsing agent which provides various services in an integrated interface to help a user navigate through a content-rich website. The third is designed to help users find on-line papers in computer science.