Like its rivals the PS2 and Xbox, the GameCube had the ability to go online – although it didn't get the kind of software support to make this an entirely worthwhile venture. Due to this, the official GameCube Broadband Adapter is quite expensive – and not worth the effort, as the console's online functions have long since been abandoned.
However, a new community-made (and open-source) accessory has been developed that not only replicates the performance of the Broadband Adapter at a fraction of the cost but also enables exciting homebrew applications – which include adding online play to games which previously lacked it.
Webhdx's ETH2GC is available in two variants - Sidecar and Lite. The Sidecar version can be purchased either as a DIY kit for $35 or fully assembled for $45, while the Lite has a $15 DIY option and a $25 assembled version. The Sidecar one is the more desirable, as it can be installed out of the box without impeding the use of the Game Boy Advance accessory.
Working in conjunction with the popular Swiss homebrew OS, ETH2GC takes your GameCube online with relative ease – and opens up the potential for some amazing fan-made projects.
For example, developer Kirbymimi is working on a multiplayer version of Zelda: Twilight Princess, and has also patched Mario Kart: Double Dash!! so that it includes online play. The ETH2GC also allows you to connect two GameCube consoles together for local multiplayer, as well as rip GameCube games to your PC.
Check out Macho Nacho's amazing video on the ETH2GC at the top of the page if you're keen to know more.