One place to start looking is the MODS Implementation Registry <http://www.loc.gov/standards/mods/registry.php>. Certainly not all MODS implementations are listed there, and some entries are out of date, but you can get a general sense there. The University of Illinois runs a registry of OAI-PMH data providers with a series of very interesting reports on various features of those repositories. The one on "distinct metadata formats" <http://gita.grainger.uiuc.edu/registry/ListSchemas.asp> shows some repositories sharing MODS via OAI-PMH.
As far as where you'll find it, although MODS was intended to be useful outside of the library community, that's where its main take-up is to date. I'm sure we'd all love to find a way to broaden its appeal to other communities, however.
Digital Library Program
Indiana University - Bloomington
Wells Library W501
Inquiring Librarian blog: www.inquiringlibrarian.blogspot.com
> -----Original Message-----
> From: Metadata Object Description Schema List [mailto:[log in to unmask]] On
> Behalf Of Jeff Jackson
> Sent: Wednesday, April 14, 2010 12:36 PM
> To: [log in to unmask]
> Subject: [MODS] MODS Data
> Dear Colleagues,
> After reviewing the MODS Schema, I am confused about one thing...who is
> using this schema and when would I encounter it? I work with data from
> sorts of bibliographic databases and have yet to encounter any "MODS"
> data. Please advise.
> Kind regards,
> Jeff Jackson