(Please see this question and comments on it for where this proposition originates.)
How would people feel about a question of the form 'What are some good examples of puzzles of type X?', inviting answers of the form '[puzzle] >! [solution]'?
There'd be no accepted answer, and the most popular puzzles would rise to the top. According to Josh Caswell and the meta references he linked to, this is not a desirable form of Q&A on SE as a whole - but the same could be said of challenge questions, and we discovered that those are certainly allowed here! I think this would be an excellent way of stopping too many of the same type of puzzle building up (imagine if we'd had a question 'What are good examples of Security-to-the-Party puzzles?'), provided there are only going to be a reasonably limited number of answers: for instance 'What are some good examples of riddles?' would be far too open-ended, but 'What are some good examples of alphabet-splitting puzzles?' would be fine IMO.
Discuss! Or just hit the UV/DV button to show your (dis)approval, if that's the way things work on meta.