Hi David,
Sorry it took so long to get back to you. I don't really want to launch a specific request for property, but rather to point out that your tool - if successful - will provide a great avenue to expose all kinds of interesting knowledge that will require many more properties than I could think of.. Just one quick example. Browsing this page
https://en.wikipedia.org/wiki/Crowdsourcing , I noticed the following interesting little tidbit of knowledge: "Domino's Pizza, Coca Cola, Heineken and Sam Adams have thus crowdsourced a new pizza, bottle design, beer or song, respectively". I wanted to add statements such as "Domino's Pizza --- crowdsourced -- pizza design".
Obviously not the most important statement in the world, but a collection of many statements like that would give a picture of what the new action of "crowdsourcing" can be used to accomplish and hence might be interesting and useful to some people (at least a few people in the long tail such as myself).
Again though - the plea here is not for a specific property, but a better/faster mechanism for expanding the property collection and for engaging larger numbers people in creating wikidata. And I think your tool or its descendant could be a great step in both of those directions.
-Ben