Siri’s a smart little moppet, but she can’t do everything for you. You can’t ask her to find you a picture of a dog from Google Images, or see if the guy you have a blind date with that night is a registered sex offender, or really do anything that Siri and Wolfram Alpha aren’t already programmed to do.
The good news is that Siri hacker chpwn has teamed up with GitHub hacker Aman Gupta to figure out how to add custom Siri commands. The bad news is it’s quite complicated, and there’s no way to do it right now for yourself.