There is an unofficial Google Speech API that has been modified and published on this blog . This article shows you how to access it using Perl, but it gives you enough information on how to do it in another language. The problem with using the unofficial API is that it is subject to change without notice and there is no support or documentation.
Nuance has a mobile SDK for speech recognition . I think there is a web service under the hood of this SDK. I know that Nuance has acquired a cloud-based speech recognition service, but it was not clear to me how they included it in their product line.
Another commercially available Nexiwave service . It uses the service provided by YapMe, but it looks like it is no longer available.