Well there's an awful lot of examples out there of people doing things for free, be that Wikipedia or Linux. Even Khan Academy was created for free.
It's an oldie and all, and I'm sure you've seen it already, but
[video=youtube;u6XAPnuFjJc]http://www.youtube.com/watch?v=u6XAPnuFjJc[/video]
I note that bankers and financiers in London give up their time for fr- oh wait...
![Wink ;) ;)](/forum/styles/default/xenforo/smilies/thumbsup.gif)