MyFax has been featured recently by two journalists that focus on environmentally friendly technologies. GreenTech Pastures "Considering the Green Profile (or lack thereof) of Common Fax Machines" and Eco-logic "Nixing the Fax" (it's a TV profile - scroll down to find the segment).
Compared to using a regular, plain-old fax machine, an internet fax service like MyFax is much more 'green'. Fax machines are always on, waiting for an incoming fax - and wasting power while they wait. They also, of course, consume lots of paper because each and every page you receive is printed - this is an obvious waste of paper (and paper production is a major source of greenhouse gases).
So MyFax is very fax- it reduces energy use, paper consumption, greenhouse gases - and saves you money.