www.blueface.ie offer a fax number. They give you your own fax number, and the faxes come in PDF format.
I remember I used to use the windows fax software to send faxes (mainly CVs) directly from MSWord etc. You need a phone line and a modem though. I'm not sure how this would work, or if it would work with a broadband connection.
Ive got eircom broadband, and for the ocassional fax I use a seperate phone cable, plug it into the modem socket and dial out independent of broadband and works fine.Alternatively, temporarly unplug the phone line from the ADSL filter and plug it into the modem socket. Its not suitable for regular use, in which case use the previous suggestions.