I stopped using a fax machine some time ago.
As rmf says, there's a lot of software available.
You sometimes need a bit of lateral thinking if you need to scan a document that you haven't produced on your computer.
I use eFax from efax.com to receive faxes.
It costs nothing, and you are given your own 0870 (in the UK) fax number. When someone sends a fax it arrives as an attachment to an email. Of course, it arrives all at once - no waiting for the next page to appear.
the downside is that you have to check your emails to see if you've got any faxes, but with 'always-on' connections that's not really a problem.
They provide a viewing program which lets you zoom in, turn pages round (people ALWAYS get at least one page upside down) etc.
And there's the great advantage that you don't have to print them out to read them.
eFax also have a paid-for service with bells and whistles, but I've found the free basic service to be reliable and sufficient for my needs.