Maybe to be a bit of a downer here but there may be a provision against it at Making tax deductible gifts and contributions as I researched this when I was looking into Kiva loans. It would violate the provision that
no material benefit or advantage is received by the donor.
Just something to be aware of if you were to put through many thousands in deductions, I heard once that they don't even audit you if your deductions are less than 3K because that is the minimum cost of an audit.
Interesting, thanks for letting us all know. The Amex / MS Society co-branded donation page explicitly says "All donations over $2 are tax deductible" - I wonder if they've checked this out and these donations are still tax deductible somehow, or if they are unaware of the above provisions.