Microsoft Bing Translator SDK allows users to convert languages in web and client apps. Instructions to subscribe to the Microsoft Translator API are available. With this SDK, developers can create projects useful to reach international audiences, manage e-commerce sites, and convey messages to multicultural users. This SDK supported by Microsoft Bing provides all documentation on the site.
iKnow, a social learning site launched last month by Japanese company Carego, have launched an API (our iKnow profile) to allow third parties to "add a little Learning and Linguistic magic to [their] applications, widgets and other mashups." iKnow allows users to take virtual English and Japanese language lessons (other languages are promised for the future) and guides and tracks their progress. Through the social component users can share their progress with friends, leave comments, keep journals, and compete for rankings.