It definitely sounds like a good fantasy/role play for the two of you. If you are curious about taking it further - talk to her about it...
I agree with K. that sometimes, it's the idea of something more than the actual act that is a turn on. But if you do want to take it further, a couple is a safer alternative than a single man or woman - they have stake in the game so to speak.
AdultFriendFinder is a good website to look around and check it out and talk about it. There are also more niche sites out there catering to more specific fantasies and fetishes.
I would also recommend that before bringing any other person into your sex life that you talk about your fears and insecurities up front and make sure to talk about boundaries and ground rules - know the rules before playing the game. That way you can both come out winners.