I use Intellifax for outbound faxing.
You set up an account with these guys, deposit like $20, and your outbound faxes are deducted at a rate of 7 cents per minute (U.S. & Canada). No monthly fees for outbound-only service.
To send a fax, you just make the destination phone number part of the email address ("12135551212@intellifax.com") and attach any file you want (Word, PDF, Excel... etc.). You get e-mail confirmations and no charge for faxes with errors.
Obviously no phone line is required for this service. Great for those of us using laptops with wireless connections, or broadband connections. Send from anywhere - even from a school lab or hotel room.
Works great!
