The Snipcart PHP Sample Code by Snipcart demonstrates how to integrate eCommerce features interacting with Craft content management system. Source is available at https://snipcart.com/blog/integrating-snipcart-into-craft-cms/
If it's speech-to-text services you're after, Vocapia Research is in the game, offering a variety of speech technology services and working with their clients to adapt, fine tune or create products that are relevant for specific applications. One of Vocapia's products is the VoxSigma speech-to-text software suite that is suitable for many languages and a variety of audio data types. The VoxSigma API is available as a Web service via a REST API over HTTPS.
Microsoft has just announced the availability of the Microsoft Translator Hub for commercial use, including access to the Microsoft Translator API. Microsoft Translator Hub is built on Windows Azure, and provides tools for businesses to "build, improve, and deploy customized automatic language translation systems."
As a translation service powered by human translators and accessed via an API, Gengo has a fairly unique business model—an API-as-product that uses the API to engage a human workforce to carry out sophisticated business processes.