Those are called BRIDGE or CLIENT devices. If you have a wireless router, then it will not work as a bridge or client unless it offers such a configuration.
I have a bridge device connected to an ethernet switched hub and it has more than one device wired to the switched hub. Works.
I have a wireless router in one room of the house and would like to connect a couple other components (Tivo and Xbox) in another room. I am wondering if I could just by another routher or is there something out there that I can set up to bridge the gap? Any help would be appreciated. I notice there are wireless game adapters but that only has one ethernet port. I would need at least 2. Thanks for your input.