monkeys audio works for sure.

I just had the first occasion of working cross-planet (collaborator is in Oz) and his 320 kbps 4-bar loops were 119.8 bpm, but should have actually been 120 bpm.

When it absolutely has to be locked in, monkey's audio is the way to go. Pretty sure I turned on Bob to Monkey's Audio and others here at PG (well, I think Bob was the only one who paid attention) about 4-5 years ago.

And to send those big files, nothing seems to work better for me than www.yousendit.com

-Scott