you can also use tiger to send faxes over the phone line if your mac has a modem. you can set it up in system preferences--->print & fax. once you've done that and have plugged the phone line into the computer, you can send any document as a fax from the print dialog just select "pdf" in the lower left followed by "fax pdf".
i know this doesn't use the DSL line specifically, but it does let one use the computer in lieu of a fax machine.
