The Sega Dreamcast marked the end of Sega's storied hardware career, but it's revered by hardcore and classic gamers despite its swift demise. The Dreamcast may have been underpowered compared to competitors like the Sony PlayStation 2, Microsoft Xbox, and Nintendo GameCube, but it was far ahead of its time. It was the first console to boast a built-in internet connection, something now considered standard, and it was also first to allow online multiplayer gameplay.
Plus, it was just a weird little system in a lot of ways, especially in its curious memory card: The Visual Memory Unit, or VMU, was actually a self-contained portable system with its own screen, sort of like a beefed-up Tamagotchi. It fit into the controller and could actually be used as a second, private screen during regular gameplay. It was never really exploited that well (my only memory of it is displaying "Rad!" during games of Crazy Taxi), but had lots of potential--privately selecting plays in sports games, for example.
The Dreamcast is pretty outdated now--it's more than a decade old, after all--but if it was made open source shortly after it was cancelled, who knows what developers and hackers could have done with it. We could have seen VoIP internet calling, chat, or media purchasing. We could have seen real games for the weird little memory card. Who knows?