First, we briefly discuss the very idea of tradable quotas, looking at a set of cases in which it has been proposed (but not implemented) outside the realm of pollution control and natural resources management. Next we study a proposal of tradable procreation quotas. We generalize Boulding's 1964 idea and discuss a full scheme able to deal both with under and over procreation. We then look more specifically at three effects of the scheme on income inequalities: differential productivity effect, differential fertility effect and tradability effect. Finally, we consider the migration dimension and discuss two possible schemes: (1) a domestic scheme of tradable emigration quotas among skilled people, serving as a possible alternative to a Baghwati tax (with different properties); (2) a regional or global scheme of tradable immigration quotas of unskilled workers in rich countries, serving as a burden sharing mechanism. Special attention is given to some conjectures regarding the impact on education and average income back in the (poor) countries of origin.