I wonder if there is already a mapping/converter/XSLT from the
Medline/Pubmed XML format to MARC(-XML) I could use.

At the moment we convert lots of data sources to a proprietary internal
format but since more and more sources are available in MARC (even in
Germany), we think about changing to MARC so we can use all the
available tools that exist to deal with MARC data (I know that new data
models are at the horizon).

The main data source that doesn't seem to be available in MARC is
Medline. Even if there is no converter, perhaps sample data could get me
going.

-Michael