The biggest for me is the Dreamcast BUT, a close second is the GBA e-Reader.
It was an interesting concept, and me having been a huge Yu-Gi-Oh, Pokemon, and Digimon (specifically Tamers) fan at the time, got me super excited to have another card related product to collect, and Nintendo related at that! But it worked maybe half the time, and for the NES games, I think you had to have like 5 cards because the cards themselves could hold very little data. But it was a cool way to add some new content to other games. DLC before DLC if you will.
Obviously there would be no reason for this kind of product now, but it would've been great if the rough edges were smoothed out so it could've lasted a lot longer than it did.
You called down the thunder, now reap the whirlwind
