What's the best accessories to listen to mp3's on the n800 wirelessly?

After I bought the thing I realize that the bluetooth part of the n800 does not play music/videos in bluetooth headsets. There has to be some kind of accessory attached to the headphone jack.

I'm familiar with bluetooth dongles that transmit bluetooth to headsets but those are usb. Do headphone jack dongles work well? There are nice dongles for the iPod...anything for the n800???

Portability is a huge deal. I'd like to be able to relax on a plane for 4 hours. Do any transmitters last that long?

Miguel