How can I send an audio file to My fiancee on her Blackberry? I can't seem to find any way to do it.
In the Messaging application when composing a new message click Menu > Attach
A popup should appear that allows you to attach pictures, captured picture, video, captured video, recorded audio and a slideshow.
Does that work for you?
You CAN send files over Bluetooth though since the DROID supports the OPP (Object Push Profile) for Bluetooth.
Not sure about audio files though since I have not tested it, but if you press and hold an audio file and click Share one of the options should be Bluetooth.