Do you guys use any instant messaging programs? How large are we talking? (hehehehe) If it's not too big you could send it over an IM program.

FTP allows you to upload files to a server and you can also download from the server too. If your ISP allows you to have a personal web page then they might provide FTP. If they do, just upload the file to your server and give your friend the link. He will download it via regular HTTP.

If they don't provide FTP, they will have an upload form in a control panel where you can upload files. Again the concept is the same, upload it via the upload form and give your friend the URL/link.

If you can't set up a website with your ISP there are other free web hosting sites as well. Just remember though that if you use the space purely for hosting files even if you are just sending to that one person, they may close your account as they will see it as you wasting their bandwidth.

I don't see why you can't use a file hosting thingy then just delete the file on your account once you're done.