Language repositories link or store a large number of language resources in one place. 

RepositoryDescription
All Language ResourcesA fantastic curated list of resources for lots of languages—Highly recommended
Language PlayerCurated lists of video content and useful resources in lots of languages.
r/languagelearning resources wikiUseful repository with links to subreddits containing resources for many languages
LanguageListThis website lists and ranks a few popular resources
Multilingual booksAnother website with lots of resources
Open CultureA website that lists free courses
Recommended resources from polyglot Lindie BotesA website with resources for ten languages
Language Learning Podcast ListA repository of podcasts in lots of languages