If you think back to the opening Econ 101 entry, I ran through network effects, transaction costs, rivalrous and excludable goods, and their inverse, anti-rival goods, which combine the efforts of many in an ever-building and evolving structure where rule is the more the merrier - something, while not new to the world, but dramatically facilitated by modern information and communication technology. The promise of current projects is that nothing good is ever lost, and everything suboptimal or counter-productive will in time get smoothed over and fixed. It's something that only the growing body of scientific knowledge has historically been able to achieve with its standards on sharing and reproducable experimentation forcing honesty on the system.
So far we've been talking about this sharing in terms of websites and tools non-profits (or really, anyone with a good cause) can use, but many of these tools are themselves built with programs that were themselves created by volunteers over time, and indeed are still in the process of evolution. Software that is built (often by volunteers) in order to be shared freely is called Open Source. This is a simplification of the wealth of different "flavors" that open source can take; I might as well be saying "ice cream is great" -- but is chocolate better that moose tracks? Blue Bell brand or Ben and Jerry's? As with ice cream, there are different concepts and theories leading to different styles and licensing of open source software. In general, however, the open source licenses grant you as a user increased rights, as opposed to traditional licenses which act to restrict your freedom. If you want to know more about open source flavors, I recommend starting by reading The Cathedral and the Bazaar, which compares the development techniques of open source to the more commonly encountered closed source, and then checking out OpenSource.org for an overview.
It's initially hard to wrap your head around, but with thousands upon thousands of dedicated geeks, combined with the long-term evolutionary power of sharing, some amazing open source products are available. Not one but two fully functional office suites, providing word processing, spreadsheets, presentation software and more (custom diagrams, clip art, ....) have been produced, one, OpenOffice which runs on Windows and Mac as well as Linux. Linux is an entire operating system, as capable as (really, moreso than) Windows or Linux, which is open source. It's popular as a server software, running strongly on less powerful machines with higher stability and security, but is also available customized for the desktop.
Even if you're not yet ready to jump into the deep end, there are many open source tools which work on the unfortunately all-to-commonly encountered Windows desktop. You can escape the trap of Internet Explorer (IE), whose latest version has cribbed all its improvements from the Mozilla line of browsers (Firefox being the most well known) -- tabbed browsing, good pop up blocking and more have been available to Firefox users since the late 90s, and only now in 2007 has IE gotten around to implementing it. Firefox and it's cousin, Flock, deserve their own full post to explore their incredible potential at marrying web 2.0 technologies and improving their functionality.
Have friends on multiple Internet Messenger programs? Have to run MSN, Yahoo, gChat, and AIM all at the same time? There's a program called pidgin which can combine all of those memory-intensive and computer-hogging programs into one simple and functional IM client.
Upgrading to the latest Microsoft Office too expensive for too little benefit? OpenOffice lets you read and write Microsoft Office files, as well as the Open Document Format, a format that's gaining steam as a standard for many government agencies tired of being locked into Microsoft's proprietary format.
This is quite literally only the tip of the iceberg. I highly recommend checking out the OpenDisc for a greater sampling of open source projects. While you're at it, breeze by PortableApps.com to download an entire desktop suite to your USB thumbdrive so you can always carry around your new favorite Firefox browser to random seedy international cybercafes and never worry about having some insecure IE toolbar stealing your private information!
The next big entry will move from your desktop to your web server, and talk about how you can use OSS software to install blogs, wikis, photo galleries, entire soup-to-nuts content management systems and more for your organization.