Several, I think. The most significant I remember were from Sweden and Finland.
Any pointers?
Maybe http://www.ksamsok.se/in-english/ , but I know more about http://data.nationallibrary.fi/bib/sparql and related.
Maybe one of the locals has more information.
The link to k-samsök is excellent and should provide you with necessary information. Remember that linked open data doesn't equal SPARQL endpoints.
Best regards, Jan Ainali