Bezier Games has just released Start Player. This is a deck of cards, each of which contains a unique rule as to who will start the next game. The idea is to use these cards during game group, or something like that. Before each game, you draw a card to see who starts. Cards say things like "The tallest player starts", and so on.
It's not really a game, it is a game accessory. I have a little metal hand spinner that I got from Sunriver Games at the first BGG.con that does the same thing.
Other game accessories include alternative dice, dice towers, card protectors, box protectors, Plexiglas covers, storage trays (mostly for war games and all their little chits), and specially designed notepads for keeping score. Not to mention the many game related items like tee-shirts and bumper stickers sold at many places.
Our game industry is so small altogether, it is hard to believe that it could even support a secondary market such as this. On the other hand, game accessories are useful for all types of games. So even if a particular game in the market only sells five thousand copies, there are still thousands of these games. And you only need to capture a small percentage of all gamers.
Also, hobby gamers are demonstratively insane to begin with. Who else would pay for game after game costing $40 or more retail? If they're rich enough to plunk down a thousand dollars for games, they probably want some cool meeple bookmarks, too.
P. S. Note the game being played in the Google Summer Code Jam's European Group. Anyone know the players? (via my son, Saarya)