Here's a few things to try asking it (I have, they produce noteworthy responses). I've been kicked out of the mall's apple store before.
-iphone, what are you wearing?
- hal, open the pod bay doors (you might have to ask it two or three times in a row)
- if you ask "iphone, find me a prostitute", it will pull up escort services
- iphone, what is the answer to life, the universe, and everything?
-if you ask it the meaning of life, it'll give you one of a few touchy-feely ******** answers about loving everyone or something
-I asked it "iphone, what really happened to steve jobs?" and it did a search and pulled up some conspiracy theory that said bill gates offed him, haha
-to prank someone else's phone, assuming they dont have the passcode enabled....activate siri and just say "iphone, call me (moron, ********, assmuncher, ect)". It'll change the user's name to that, so the next time the owner asks a question their phone will call them ********. I changed all the iphones in the apple store to various insults, an employee saw me doing it and thats when I got thrown out of the store, lol, but not before some little asian woman asked it something and shortly thereafter seemed very shocked. This is actually highly entertaining should you not get caught, to then go hang around the ipads(which are adjacent to the iphones) and watch the merchandise insult the customers.
-If you insult it, like "iphone, you're totally worthless", it'll say something like "well, I beg to disagree, but you're entitled to your opinion"
But yeah, the siri thing is pretty amazing. Talking to computers (as in to a computer, not to a person via a computer) still kind of seems weird to me.