Is there a service that can search for answers to general questions? I was looking for an API service where I can ask it a general question (for example, when was Einstein born?) and retrieve an answer from the web.

Is there any available service to do that? Have tried Watson services, but didn't work as expected.
You can use Google

https://encrypted.google.com/search?hl=en&amp;q=when%20was%20Einstein%20born
and parse the response.

Wolfram ALPHA is another candidate.

http://m.wolframalpha.com/input/?i=what+year+was+Einstein+born&amp;x=0&amp;y=0

You can parse the returned html and see "Result:" div.