Resources for programs teaching natural languages

What API's and data sets are available for use in programs to teach natural languages e.g. to aid in learning to read/write/listen/speak a 2nd language? These could be web or traditional API's to dictionaries, translation services, associations of words / concepts to images, sounds e.g. spoken words or phrases, movies, or sets of flashcard decks. Also of interest are websites that could be spidered to obtain local data sets for offline use.

As a start, 开发者_StackOverflowI note that that the Google translate API can be accessed programmatically.

There is an online web course for Swedish with sound files. There are online texts and MP3 files for many languages including Swedish from the Foreign Service Institute.

I am especially interested in resources for Swedish, but feel free to add resources for other languages. Please tag any answers with the relevant language or languages.

I think spidering sites that provide language learning content is against the ToU for most of them.

If you're interested in attempting to analyze pronunciation and grade its correctness, this API may be worth referencing. I don't have personal experience with it, however - algorithms for this are really still in their infancy, and don't provide a lot of value to the average consumer at this point.