I find them useful for searching for some function or API name with natural language. 'What's the function call [in blah] that generates a quaternion from a couple of vectors?' type stuff. Not exactly inspiring but I've found it highly useful. If you try to search for something like that online (and somebody hasn't asked the exact question on e.g. stack overflow) you'll just end up getting all the documentation for quaternions, vectors, and blah - when the function itself might even be in a tertiary math library.