Receive and Send Faxes From Your PC without a fax machine:

For incoming faxes, you can use eFax (http://www.efax.com). The service will give you gives me a free fax number with an area code that's somewhere in Ohio. Faxes can be delivered to your inbox as an e-mail attachments. There's no charge; there's no limit on the number of incoming faxes; and you will only get occasional spam from eFax pitching upgrades.

To fax documents from your PC, you can use Fax1 (http://www.fax1.com). You pay a paltry 12 cents per page, and you get a dollar in credit to try the service. Fax1 can be used for incoming faxes, but it charges $9 per month for that service, while eFax receives faxes for free.