Question in point:
https://gaming.stackexchange.com/questions/11700/what-are-all-the-games-in-the-mama-series
I don't consider it in any way or form related to game-rec. The only possible flaw here is that it might fall under the "too trivial" clause, but in this specific case the asker said he specifically looked online for that data but could not find it, only partial lists.
However, apparently others disagree - badp considers this being close to a game-rec or a game catalog, something I don't quite understand. It does ask for a list of games, yes, but that list is finite and absolute - there's no game that is maybe on that list. From my comment on that question:
A catalog is more where each user can contribute an answer of its own, and all can be valid. Here there's only one possible correct answer - the one that lists all the games in the series. Any other answer will be an incomplete one.
I might be missing something, though, and I would like to hear more what the community thinks about it.