I see Giving Coupons as a mechanism for fundraising. As opposed to traditional fundraising ("Please give us money"), Giving Coupons aims to be more participative ("I'm giving money to charity, help me decide which one!"). Giving Coupons tries to introduce a social/interactive element to catalyse charitable giving.
I think you are right that it is a burden. I think most fundraising leverages on some amount of guilt implicitly ("Please donate, or else these people would suffer"). But all Giving Coupons is asking you to do is to go to a website and pick a charity, and even if you discard the coupon, no money is actually "wasted", the donor can simply redistribute the coupon when it expires.
On privacy, the people's choices in aggregate are necessarily known to the organisers. But individual choices don't have to be revealed. Currently, coupons are serialised, but donors do not see choices on a coupon level. Alternatively, coupons may not have to be serialised, assuming coupon receivers can be trusted to only submit once.
One way to measure the viral effect is to count how many people start campaigns after receiving coupons. Another way is to measure the number of campaigns started divided by the number of coupons redeemed, for any given time period. Optimistically, we will know it's viral when the number of campaigns grows exponentially.
Hi Rasool, thanks for your questions!