I found FaxCenter while looking for a replacement for the limited fax capability built into Mac OS X. I'm glad I did.

This is a close-to-perfect example of great Mac shareware -- it's simple, elegant, and gets the job done well. It took me a while to get it set up -- I should have read the docs first, as you really do have to make sure that the BSD subsystem is installed -- but if you follow the directions it's easy.

My favorite feature is the ability to combine multiple documents into one fax. The abilities to customize the cover sheet and to send quick notes straight from the program are great too.

The bottom line is that I like it well enough to pay for it: I just sent in my $10 to the author. Give it a go, I think you'll like it too.