This repository (also a dat archive! see below) is an index of "early days" (say the first year or two) of dat archives. These archives (say, up to a few thousand or a few hundred gigabytes total) will be preserved by the Internet Archive (archive.org).
Of particular interest are early experiments, tests, demos, and creative content.
Dat link: dat://839b8c03f2ce67cc0b2c8e88dbf35eb1ff7f81d115afa72e07c5b1803a663ec4