I'm looking for a unusual OAI endpoints (different implementations,
different metadata schemes or extensions to schemes, different
structures, unusual content types, etc) to test against. I'm aware of
the list a couple of mainstream lists of which
http://www.base-search.net/about/en/about_sources_date_dn.php?menu=2
is the most comprehensive  the and the live demos of dspace, eprints
and fedora. But I'm looking for more obscure installs and corner
cases.

Does anyone know of any other candidates?

Implementations known to be buggy, broken or dubious especially welcome :)

I'll publish a list of endpoints I find useful.

cheers
stuart