Screen cover. iPhone users know what I'm talking about.
Third-party dock that allows for use as a horizontal photo frame. All you need is a stand that secures the iPad and a power converter that goes from a standard AC plug to the 30-pin iPod connector. It probably will be a little cord that plugs in, so not a snug side-docking connection. But I want to use it as a digital photo frame when needed, so this would be my preference.
iPhone tether cable. C'mon, I can dream!
Bluetooth stereo headset and/or speakers. I probably won't be able to afford these, at least the speakers, but no need to clutter a very wireless device with any headphone or speaker cords. I don't plan on jammin' to the music from this with the built-in speaker. Unless Bose is making a speaker that small, it's not going to be much more than the iPhone speaker.