You may have seen the newest MasterCard commercial promoting their link with Stand Up 2 Cancer. For every purchase you make using your MasterCard, they will make a one cent donation to this organization, up to a total of 4 million.
Now I applaud them wanting to do something right, but is this really it? I strongly suspect that they are spending more than 4 million dollars on this ad campaign, which really means this is more about them looking like good corporate citizens then actually helping people. (According to Advertising Age, they are #93 in leading national advertisers, spending $343 million in the US))
Here's the other part, by using your credit card (with an average interest rate of 14.88%), you are getting them a tax write off rather than getting a tax write off yourself by making your own donation, while at the same time making them a lot of money that's not doing anything for you.
Now I did some digging to try and find what MasterCard profit was last year, and the best I could come up with was from Wikipedia which has them at a net income of 1.846 billion, on revenues of 5.539 billion (and operating income of 2.757 billion).
If those numbers are correct, that means that MasterCard is donating .002% of net income, or .000072% of revenue, to cancer research. Wow, that's mighty generous of them. I hope they don't get too carried away.
Don't make a donation to MasterCard, instead make your donation directly to the cancer charity of your choice. They and you will be much better served by this arrangement.