Lydia (or somebody operating the @Wikidata handle :) posted this question on Twitter and a few great ideas started trickling in. 

I went ahead and created an AllOurIdeas poll, seeded with the first ideas posted on Twitter, to crowdsource the generation of new ideas and produce a robust ranking.

If you're unfamiliar with AllOurIdeas, it's an open consultation engine allowing people to choose which idea they like best via pairwise comparisons (I am cc'ing Matt Salganik, the project lead). It's very simple on the surface but it uses algorithms such as the Condorcet method to test how strongly each idea performs against another, reducing the weighing of the oldest ideas to create a level playing field for newly created ideas and preventing gaming or self-promotion of one's own ideas.

Try it out or post new ideas: the more votes it gets, the higher the confidence of the ranking. Real-time results and statistics are here.