Before I get started, I need to tell you that I want to have an
internet business which gives 50% of the revenue to charity.  The
concern I have is that I do not think that any of my customers will
believe that I will actually give 50% of the revenues.  So, my
question-

Is there a company which can take my donation money, give it to the charities I
choose, and then post it on the internet for the public to see the
amount that I have donated?

Or is there another alternative?

You do mean 50% of profit, not revenue, right?