I just found a question on Stack Overflow which could be a very good example of a question for the Lego Mindstorms site.
Could there be a way for me to mark this question (from, as an example, the Lego Mindstorms proposal page) as a good example of question? Typically, I would think about adding a text field allowing one to enter the question URL. Then, Area 51 would use an internal API to grab question text, and some associated information (like its upvote count, resolution status, and so on).
EDIT: most of the single reply and comments focused on what I said, omitting the fact, like me, that this question was to have a life in an Area 51 proposal, so let me extend this example a little further.
Once the Area 51 site (in my example Lego Mindstorms and robotics) will have reached the beta state, and for this site to be correctly seeded (like the Stack Overflow crew gently explained us), it would be very interesting to have already replied questions. As a consequence, if I find a question on any previous site that may be a "great example", and if that question is marked as answered when this Area 51 site is seeded, it will benefit from already existing content, no?
This is why I think using the question URL is way more interesting than doing a simple copy/paste, and loose all the metadata (and future updates to that question). As a developer, I understand this feature would take some time to implement, but I consider it an interesting way to feed the upcoming sites.