of SourceForge writes with an interesting way to look at the value of certain free software options: "Apache OpenOffice 3.4.1 has averaged 138,928 downloads per day. That is an average value to the public of $21 million per day, as calculated by savings over buying the competing product. Or $7.61 billion (7.61 thousand million) per year."
(That works out to about $150 per copy of MS Office. There are some holes in the argument, but it holds true for everyone who but for a free office suite would have paid that much for Microsoft's. The numbers are even bigger if you toss in LibreOffice, too.)