I definitely had a keyboard for my Dreamcast. It was my first internet enabled console, as well as my first exposure to online gaming with strangers (previously I had only done direct TCP/IP connections with friends on games like Diablo 1 and Starcraft). Phantasy Star Online was so damn addictive.
There were two (firmware?) releases of the Dreamcast keyboard. The first release would allow TWO KEYBOARDS to be used with the game. The later release keyboard would only allow a single keyboard to be active at a time. It was a lot of fun yelling at your teammate to type faster, which of course made both players more flustered and do poorly.
I learned how to type with this, at the age of 22 as a full time software engineer! I never knew how to touch type, but then I somehow landed a software engineering job. I figured I needed to learn, so I downloaded this and played it so much. Good times.