Since I started Sampa I thought on ways that I could make donations part of our business. The problem is that we don't have any hard cash to donate. Our revenue is so small that even if we donated 10% of it, it wouldn't make a difference. We also don't produce anything that we could donate in kind and our service is already free, so charities can use it anyway.
However, just a couple of weeks ago I had an epiphany.
We could point hundreds of thousands of web pages to a charity and have a dramatic impact on their PageRank as well as referral from a Sampa sites. If we assume a low CTR like 0.5% we could generate more than 100 clicks per day to charities. The "web value" those clicks can be the equivalent of thousands of dollars per month if you are buying a CPC or CPM campaign.
But you might challenge me and say that telling users to add a link to a charity is just a 3-4 step on any web service. We removed most of those steps and made it a single step during the sign up process. Now, when you sign up for Sampa you have a immediate opportunity to choose a charity. Even if you are super lazy you can do it.
Another way to incorporate "Charity Giving into your Business Model" is something like the "stock tithe": http://www.stocktithe.org/case.html . It doesn't cost you or your customers anything, comes out of your founding stock, yet integrates charity into your business motivations.