Having it go to the first friend encourages an obvious bias, although that just depends on how much you trust that friend. Having it all go to you, the site owner, seems a bit unfair (a massive reward/effort ratio!) and nominating a charity would be an excellent way of mitigating that. I've heard of a similar incentive-based scheme in which you pay money to an entity you dislike (e.g. democrat donating to republican party) if you fail.
