I will always vivdly remembering my Dreamcast. I got it at a local shop run by a pretty cool guy at a mall that is now shut down. I bought it with Soul Calibur even though I'm not a big fighting game person, but I still really enjoyed it. I had a lot of fun with the DC up until its ignominious death (and Sega USA being run like total shit didn't help matters much with Sega Japan being so weirdly fucked up).
By far and away I spent the most time with Phantasy Star Online and a pretty solid group of people until it was killed off, but there were some pretty interesting/unique titles on the DC.