Mergent Corporate Actions and Dividends API
From http://www.programmableableweb.com:
Provides information on corporate actions and events reported by US and Canadian publicly traded companies, including a detailed database of issued and declared dividends. The API allows access to detailed data on dividend distributions, stock splits, stock dividends, spin-offs, redemption of stock, rights, tender offers, mergers & acquisitions, bankruptcy filings, and more.
Another corporate finance information source that can be usefully combined with other information.