You Send It
No sign up required; you enter the recipient's email address, pick the file, (and, if you want to, put in your email address and a message), and click send! Once you upload the file, it will send an email to the address you put in, with the link for the download. And it works for files up to 1 gig!
The link will expire after seven days or 25 downloads, whichever comes first. I like it because its easy, and there is no sign up needed!!