It's a huge nostalgia trap for me too. Probably because we can't go back. There's nothing else that brings me the same feeling. For people of a certain age, it's almost like being homesick for the house you grew up in. Sometimes I'll dink around setting up a Syncronet board or connect to House of Lunduke or something, but it's never the same. You just can't recapture the magic.
In retrospect it was such a brief, intense love affair. For me it started in 1990 when I bought a modem from the back of a magazine in high school, installed it in my Tandy 1000 myself, and used every penny of pay from my job on long-distance calls. When I went to college I was the only student in the dorms who could dial into our school's Sun System and telnet to ISCABBS, so our room became a late night hang out for friends every night. I still visted ISCA for a while at my first job out of college, but it just petered out as the web became prominent.
What I would give to discover a new technology that inspired so much wonder and optimism.