The new feature can be found at the bottom of your profile's page. You can export your game collection or the games still missing in your collection into a CSV or a TXT file. Some filter options are available as well as a switch to turn off the japanese kanji/kana characters, for those whose computer has some problems reading them.
Be sure to use this new feature and buying the same game more than once because you forgot if you already own it is definitely a thing of the past. There are only few things considered more professional than walking into Super Potato or Retro Friends, armed with your to-buy list, and browsing through the shelves looking for the games on your list. You can even fake some japanese language skills if you want to.^^
N-Joy :)PCE Daisakusen Team