Academics know JSTOR as an online repository for research published in prestigious journals. The repository reaches quite a ways back in the past. The JSTOR project now has an online “data for research” service. From the “about” page to which the previous link points:
Features provided by the site include:
- Full-text and fielded searching of the entire JSTOR archive using a powerful faceted search interface. Using this interface one can quickly and easily define content of interest through an iterative process of searching and results filtering.
- Online viewing of document-level data including word frequencies, citations, key terms, and ngrams.
- Request and download datasets containing word frequencies, citations, key terms, or ngrams associated with the content selected.
- API for content selection and retrieval.
ADDED: credit for this goes to Amanda French, whose tweet pointed me to the data for search service.