( I've not found anything about this, so I dare a new thread..)

Do you want to enjoy music from your ITT on loudspeakers when no mains current outlet is available ?

Try the Denver TR-43 :
www.denver-electronics.com :
COMPACT FM RADIO WITH TELESCOPIC ANTENNA
AUX LINE-IN FOR MP3 PLAYER
HEADPHONE JACK

POWER SUPPLY:230V~50HZ OR 6 X SIZE “AA”
BATTERIES (NOT INCLUDED
UNIT SIZE: 95 (W) X 156 (H) X 106 (D) MM
UNIT WEIGHT: 0,616 KG

Price in Sweden 100-170 SEK (approx. 10-15 $ or less)

The sound quality is clearly above average for the price.
The FM reception is just average.
The housing is a sturdy plastic box and the loudspeaker is well protected.

I have enjoyed (even complex) music for hours with two of these attached in stereo to my N810.
Battery life: not tested, upto now 5 hours of same quality on one set
The small loudspeakers offered by manufacturers of cell phones (at least those I have seen) come far behind in sound and build quality.

P.S.: For headphones, try the Koss Portapro, good sound and they fold into a bag smaller than my fist.