QUOTE (colore @ Jul 14 2008, 06:42 PM)

how do these work?
It's just a very simple and basic slip ring assembly (brushes and rings). So your wire can rotate freely.
QUOTE (colore @ Jul 14 2008, 06:42 PM)

also, maybe a very thin retractable cord exists?
That would have to have some kind of spring always pulling on the cable (annoying), or requiring you to rewind it after use (no thanks). Besides, we used coiled handset cables for a reason. It's an effective system that works fine (besides the tangling).