I just ran across a handy service called senduit, What you do is go to the page, browse for your file on your hard drive (100 MB limit), set the expiration time (30 minutes to 1 week) and hit UPLOAD. The site generates a URL for your file, which you send to whomever via email where they can download it from the sent URL. When the file expires, it goes away from the server forever.
http://www.senduit.com
I have been using "You Send It" but I like this un-bloated one better.