Enormous archive of corpora from the IDS, including several newspaper corpora, author corpora (e.g. Goethe, Brothers Grimm, and Max/Engels), and other topics.
Corpora available from DWDS that are mostly free but may require online registration. Includes corpora of prominent newspapers like FAZ and Die Zeit, as well as several topic-based corpora.
An European Union funded project which collects language technology resources from across Europe. The repository of corpora can be searched and filtered by language.