Hey I came across a new mobile site that allows you to send files from your BlackBerry to another Blackberry using wap and the internet. pretty cool if you have unlimited data and dont want to incur mms charges to send pics and video clips to a friend. Only downside is it doesnt work on verizon. Here's the link. I think it's a mobile site so you need to use your bb browser to access it

The WapXChange

Testing this, and so far, it is only hour-glassing for about 7 minutes, after hitting SUBMIT on the screen, sending a small MP3 file.

EDIT, ok nothing. It finally timed-out with nothing to the other BB.

Dont know about Mp3s. I havent tried to send one of those. But it works well for smaller files like ringtones, pics, ect.. Could be your connection. My device has an Edge connection and it works fine.