So you're a Trekkie who's always dreamed of owning a communicator. Well, they still don't exist. Sorry! But you can turn your iPhone into one, sort of, using an app.
For $2, the iPhone Communicator App opens by flipping the phone, just like the real thing. It then has all sorts of original sound effects from the series, and it has access to your contacts and can act as your phone. So yeah, its pretty much as good as you're going to get for the time being. After all, a real communicator is actually less versatile than an iPhone, right? So just be happy with this, Trekkies.