Certain polymath-flavor questions appear on MO, and are not really appropriate for the forum. Such questions are probably posted (I can only be sure for my own such posts) because MO captures a huge "mathematical experience footprint" that is unlikely to be harnessed by a blog, for example.
The present post does not so much contain a question, but contains a suggestion for better handling (and/or preventing?) such posts. Here's the suggestion: There is a plugin available that will add Q/A functionality to a WordPress blog. If someone is interested in starting a "mini polymath" project that is intended to collect the community's ideas on a particular question, he or she can start such a blog dedicated to that question...forming a "Local MO" for that question. A single question on MO (viewed as global MO) can be dedicated to collecting links to all of these local MO "polymath" sites dedicated to the more speculative or collaborative efforts surrounding a given question.
The up/down voting for a local site will not signify "reputation" of a user, but instead evaluate a given idea for its "promise". The Q/A functionality will then allow the most promising ideas and strategies to bubble to the top for a question and it's associated answers.
I'm interested in the community's thoughts on this idea.
Of course, I'm posting this on mathoverflow.meta because the single big-list question pointing to these local polymath projects needs to be suitable for MO, and the post on MO pointing to these projects would probably be the main way the local projects can be found.