Once connected to a another phone via bluetooth you can:

read his messages

read his contacts

change profile

...........................

play his ringtone even if phone is on silent
play his songs(in his phone)
restart the phone
switch off the phone
restore factory settings
change ringing volume
And here comes the best
Call from his phone it includes all call functions like hold etc.
Super Bluetooth Hack for S60 2nd 3rd devices.
Works very well on sony ericsson/samsung ans Nokia phones[TESTED]