DWANGO, which stood for "Dial-up Wide-Area Network Game Operation," was an online matchmaking service that specialized in FPS games like Doom and Quake. It has a fascinating history that you can read about more in its Wikipedia article.
I believe I signed up for a free trial of DWANGO circa 1994 so I could play Doom with someone when I was bored, but I don't remember ever getting it working for some reason. Instead, I often played co-op Doom (and later Quake) modem-to-modem with friends who called my BBS.
Discussion Topic: When was the first time you played a FPS multiplayer online? How did you set it up? (i.e. modem-to-modem, TCP/IP, services like Dwango)