But even with these obstacles, the recent successes in what could be called invisible computing are so tantalizing that the promise is inspiring a concerted effort to surmount any shortcomings. Take software agents, for instance, which are essential to integrating the PC with a person. An agent is a personal high-tech servant who keeps track of your most private information -- calendar, bank accounts, credit records, relationships, likes and dislikes -- and issues a warning when something is wrong or alerts you to something you may want to take advantage of. There are already numerous prototype agent programs that automatically negotiate airline tickets, find the best prices of items on the Internet, seek out like-minded people on the Web, or find needed information to complete a difficult task. Typical is Expert Finder (EF), developed at MIT's Software Agents Group, in which a software agent, aware of your levels of expertise in any given subject, surfs the Web for a specialist in a topic that is stumping you. To do this, the agent talks to other EF agents, getting their owners' profiles. After reading these profiles, the agent puts together a list of people it thinks might be able to help you solve a problem. Another MIT agent -- her name is Letizia -- constantly reads over your shoulder as you're browsing the Web. Staying one step ahead, Letizia unobtrusively scrambles to find other pages that are related to what you're looking at and that tie in well to your interests as revealed by prior Web sessions. When she comes up with links, Letizia explains why you might like the page she found and, if you like, guides you there.