I only use fax when people demand it of me. I'd much rather send a .pdf over email but some people still don't want to do this. Amazing. When I do fax it's from work. I've used the free fax services. They're free because they spam the recipient with adverts.
I had to sign something for my credit union, the lady there emailed me the form. I replied back and said I would sign it and email it back when she got home. Not understanding, she replied that I could not email it back because it had to be signed and I must fax it.
Later I opened the Word 2003 doc she sent me, inserted my signature .jpg, saved it as a PDF and emailed it back to her. She was astounded such wizardry and magic were even possible and asked me how I accomplished such a feat. Amazing.