HH,
The one I have in mind is Pratham (http://www.prathamusa.org), a US charity that supports primary education in my native India. The site started around Nov-2009, and I hope to make a first contribution at the end of this year.
However – just to be clear it takes a lot of 20 bucks to add up to anything substantial – so I expect the amount to be very modest. I keep the costs low, but the bulk of it comes from the cost of programming the website, and the programmers’ time spent dealing with support issues (which fortunately have been very few). There is a cost from Google adwords which is the only marketing I employ. I do want the site to be financially independent of my resources so it can carry on,
Thanks for asking.
Mukul