Matthew Robinson and Tom Wrigglesworth compared the ink economy of eight popular typefaces in their collaborative project by Measuring Type. They conducted the experiment by writing “sample” at the same point size in ballpoint pen. Take a look at the pens for further proof that Garamond is better than Comic Sans.
Measuring Type made me think of Ecofont. Ecofont was designed in order to save toner and ink when printing, thus reducing waste from ink cartridges. Also, obviously, using less ink and toner will save the end-user money. The font is essentially Vera Sans with small holes punched out of it. When used at small sizes, the holes almost disappear. The basic version of Ecofont is available for free download here, and a professional version of the font is for sale on the site too.
Measuring Type via swissmiss
The free Ecofont typeface has been developed into Ecofont printing software with which you can print with the font of your choice and print that same font with holes. So now there is Arial, Verdana, Times New Roman, etcetera with holes.
Another big advantage is that the font invisibly gets converted on the background when clicked on the Ecofont-printbutton. So on screen you see the font you always see and only the print contains the (same font with) holes.
Besides that the Ecofont Free was hand made; for the Ecofont software they programmed a solution which puts the holes in the best place of every character. So the readability is maximum.
You can print a testpage via: http://www.ecofont.com/assets/docs/Ecofont_professional_testpage_dec2009.pdf
(Of course on this page they had to use the font with holes on screen as well in order to make it possible for you to print without having their software installed)