Update 2/14/2017: The www.faxitnice.com website is no longer working. I use www.ringplus.com now for occasional faxes (they can give you a $9.99 pay per use plan if you call them)
Original post (9/5/2007) below:
I had to send an urgent fax today and did not have access to a fax machine. I signed up first for eFax. Then I realized that I could not send faxes without paying a monthly subscription. I then went to this Wikipedia page and looked at the list of online fax providers. I finally decided on FaxItNice.
The nice part about FaxItNice is that you have the option of not paying a monthly fee. And the credits do not expire. This served me well because I do not send faxes regularly. And I do not want to pay a monthly fee for something I will not use regularly. I uploaded 2 word files and 1 excel file and there were no issues sending them. I went for their Sending Only Plan which costs 18 cents per page to send faxes to the US.
Bottomline: Definitely recommended for people who want to have the ability to send faxes online.