Yes it does. Although I'm no longer a subscriber, I had a great experience with Trustfax.
http://www.trustfax.com/
The way an online fax work is by attaching a soft copy (scanned image) of your physical document on the web site fax page, typing in the destination fax number and adding your information (name, phone, message related to the fax attachment, etc).
Online faxes like Trustfax also assign a virtual toll-free fax number for you to receive faxes. You can receive faxes through their website or via e-mail as attachments (pdfs).
As you can see, this functionality is easily replaced by having a scanner (most modern printers do) and sending e-mail attachments, but some companies and individuals still prefer the fax method of communication, especially if the fax is shared among many people in an office (banks, mortgage companies, car dealers ,etc). Also the process of scanning, saving to a computer drive, looking for the file to attach, renaming a file, etc could get tedious and cumbersome for some less tech-savvy users or for people who do this on a frequent basis.