The site provides data on almost 35,000 trans-Atlantic slave-trading voyages, maps, images, data on some individual Africans transported, and educational resources. The bulk of the dataset comes from projects from the 1990s to compile the data, published on CD-ROM in 1999.
The open access movement:
Putting peer-reviewed scientific and scholarly literature
on the internet. Making it available free of charge and
free of most copyright and licensing restrictions.
Removing the barriers to serious research.
I recommend the OA tracking project (OATP) as the best way to stay on top of new OA developments. You can read the OATP feed on a blog-like web page or subscribe to it by RSS, email, or Twitter. You can also help build the feed by tagging new developments you encounter.