"Contacts don't match the way people think," said Lili Cheng, group manager of the social-computing group within Microsoft Research. A better model is the handwritten list of phone numbers many people keep next to their computer. That, Cheng said, "better represents the people that you'd want to talk to." To try to translate that idea into digital terms, Cheng and her team have come up with a concept called Inner Circle, which automatically maintains and updates a list of about 20 people with whom one is e-mailing and instant messaging the most.