funnily/coincidentally enough, a new one of those just dropped: <a href="/wiki/Betray_the_city_to_the_Constables" title="Betray the city to the Constables">Betray the city to the Constables</a> (et al.). these cash out *all* your city prosperity all at once, and city prosperity can greatly exceed a T8 in total value if you just save up 'til that point.