HCI, Human-Computer Interaction, has always been an important topic for me. Both my Master's thesis and my PhD thesis are related to HCI. I have also been involved in the HCI community in several ways.
HCI Index
The HCI Index started with a private collection of HCI-related information on the Internet. This has evolved in the HCI Index. I still maintain the list, although I no longer actively develop it.
MMUIS
In the Netherlands I am part of a group of both former and current Ph.D. students in the area of HCI, Multimedia, and Information Retrieval. The group is called MMUIS. Even though all of us now have our PhD's, we still meet from time to time. It seems the new goal is to become a professor. ;-)
ACM SIGCHI
ACM SIGCHI is ACM's Special Interest Group on Computer-Human Interaction.
I have been involved in the yearly conferences of SIGCHI for a number of years. I have been a Student Volunteer in the years 1992-1996. At CHI'97 I was Chair of Computing Support. At CHI 98 I was Student Volunteer Co-Chair. At CHI 2000 I am Co-Chair of Demonstrations. Finally, at CHI 2001 I am Co-Chair of Student Posters.
I have also been associate editor of the SIGCHI Bulletin for a while, and I have been the VP for Operations for a two-year period as well.