I know of two:
* wit.ai
* api.ai
They have similar offerings in that you can train on sentences and get entity and intent recognition to work for limited domains.
I have a few questions:
* Are there others that you use/recommend?
* Are these useful/enough for your tasks?
* If not - what's missing from them that you would like to see?
* What kind of applications do you use them for?
Thanks!