Reader-types, it is now time to listen to me push politics. Be forewarned! (Or just skip this one if you are politics averse.)
I saw this post at Alicia's blog, and wanted to add: perhaps you too should consider checking the little "please give my organs to other people once I am no longer using them" box on your license. And if you're feeling especially giving, you can give a some while alive (one kidney and a big chunk of your liver, and I think that's it).
Yes, it's a fraught subject (especially if it's a kidney), and clearly it is understandable if you have thought about it and don't want to donate, but the huge jump between the number of people who donate in countries with an opt-in system (like the US of A) and those with an opt-out (like Amsterdam or Spain) speaks to a general disinclination to check boxes, not to give organs.