I'll have to take a look at box.net, but I have a personal paranoia about people offering 'free' storage. I've used it for small stuff in the past, but they usually don't offer enough storage to be useful to me.

I had to send an Access MDB to a vendor a couple of months ago and couldn't get either Outlook/Exchange or Yahoo to cooperate! (both the extension and file size, even after compression, were working against me) Finally ended up FTPing it to my personal web site into a passworded area to get it to the guy. I've been re-reading our computer policy document and it looks like I should have PGP'd it first, so I should download the program. Funny thing was that the vendor's FTP server had just died the previous day.