Communicating cartridges

A lot of contemporary video game players take online communications for granted-after all, online services have been a standard feature in consoles for nearly fifteen years at this point. However, before the ubiquity of the internet there was a time when some clever cartridges let gamers run up to the bleeding edge of technology and peer into the future. Today, let's close out our cartridge series by taking a look at a few cartridges that offered some form of connectivity for otherwise isolated consoles. As always, this isn't a comprehensive list of everything that existed-it's just a brief survey at some of the more notable or interesting high points. I really miss the days of whacky console addons.