I'd like to see the slave trade voyages (http://www.slavevoyages.org/tast/database/search.faces) mapped in a similar fashion.

has anyone done that?

Not to my knowledge, and I agree, that would be very interesting.

This is the closest alternative so far, but the heat map visualization approach is much less granular/doesn't do as much as could potentially done with the slavevoyages.org data: http://mcb226.github.io/SlaveTrade/

Yes. If you pause and click on any of the dots, you can also see details about that slave ship:

http://www.slate.com/articles/life/the_history_of_american_s...