It's probably more hassle than it's worth for most, but I run a low-end Linux server at home to handle webhosting, e-mails, OpenVPN server, FTP, etc. About a year ago I installed the open-source HylaFax software & couldn't be happier. It's configured to receive incoming faxes on a modem and e-mail them to me as a pdf attachment. I can also send faxes on the road either via a secure webpage for simple messages or can e-mail my server a postscript file generated by Word/Excel/IE etc. for outbound faxing. If I need hardcopy on the road I'll often e-mail something I need printed to home which in turn faxes it to my hotel.

Yes it can be a pain to set up, but it's become a hobby now & for a couple of bucks worth of electricity a month the home server has been a great roadwarrior tool.