Small Business Server 2003 and 2008 both do a very nice job of managing your incoming and outgoing faxes. All you need to do it to install a FAX modem in the Server, connect the fax line to the modem, and then a quick setup will allow you to receive faxes and route them to a folder, an e-mail address, and/or a printer. Additionally, outgoing faxes can then be sent from users desktops, with notifications of the results being printed or e-mailed to an address you can specify.
This same possibility is also in Windows Server 2008R2. With FAX becoming somewhat obsolete it is a nice way to handle FAXes in a PC environment.