I had been using YouSendIt to send big files over the internet (RAR'ed albums mostly), and I was happy for a while. But then I noticed it was crap. You had no way of knowing how much you had uploaded and usually the transfer ended in an error, so I had to start all over again.
The best thing that happened to me was finding out about SendSpace which is a sort of clone of yousendit, but way better than it (not sure which one is which's clone). You have a meter to know how the transfer is going, complete with transfer rate and estimated time (besides %)
So there you go... Use SendSpace if you need to transfer something bigger for email. Up to 1.3GB!