Sega's 1999 Dreamcast is definitely a memorable one. It had a great line of games, decent graphics, and fairly good software to boot. The only reasons this bad boy was a failure were that it was born at the wrong place at the wrong time, it was sadly impotent compared to the PlayStation 2 and the very first Xbox, and it emerged during an economic crisis in Japan.
In fact, the Dreamcast was the last of Sega's consoles. Having sold less than the Saturn, the company lost heart and discontinued producing gaming hardware shortly after its demise.