The problem of many (most) social sector organizations is outreach (marketing, in business-speak). Because of a lack of budget for marketing, it's hard for potential clients to find out about the services that are available to them.
Google advertising is highly tuned. If someone is searching on the terms "Books blind," they are looking for something like Bookshare.org. It's an incredibly effective ad for us on Google: a clickthrough rate on the order of 5%. This means that one out of twenty people who see the ad displayed choose to go to Bookshare.org via the ad link.
The deal behind the Google Grant program is that Google absorbs the advertising costs. So, if that ad click would normally cost $1, it costs Benetech $0. It's a great deal! Of course, one of Google's key precepts is that lousy ads don't get served. So, your ads have to meet performance standards in terms of relevance and experience (if nobody ever clicks on your ad, it will gradually drop off to the point where Google no longer serves it).
We have recently added advertising for our Miradi environmental biodiversity software, but for the first time we ran into problems at the outset. The automated quality algorithms (which have been considerably upgraded over the last few years!) wouldn't even let most of our ad ideas be served at all. So, we turned to the Google Grants team and in less than a week they had redone our ads in terms of organization and text, in such a way that they all pass muster. And so, now people looking for "biodiversity software" will see an ad for Miradi!
I've been trying to find the similar program at Yahoo and MSN, but no luck so far. This is a terrific example of how high tech business can support the social sector with a modest (at most) impact on the bottom line. Really glad we're realizing the benefits of this Google program!