I was just going to talk about a similar research. So imagine my delight when you mentioned this!

This was actually done! I heard this in a talk by Dan Arielly (of "Predicatably Irrational" fame), which he called "his favorite social science research ever."

Basically, in countries in which you opt out of organ donation (I think these were some Scandinavian countries), the percentage of organ donors was really high. In countries where you "opt in" to organ donation, the percentage of organ donors was really low.

Okay, here is what a simple Google search yielded:

http://scienceblogs.com/cognitivedaily/2008/10/dan_ariely_at_davidson.php