I follow the regular bulletins from regularly from the Spain based organization Fabrica Cultural at www.fabricacultural.com
Through this web Rubicón Servicios Culturales y Educativos provides constant updates of information from sources in many countries in Europe. I think this site is worthwhile for readers in the USA and other English speakers because it serves as a link between Spanish based organizations and opportunities in the rest of Europe.
There is an interesting combination of links to institutional and government openings including the European Union and European Commission, national governments and universities, and private institutions.
Another fascinating feature is the range of paid jobs and openings in the volunteer sector.
Certainly worth following.