Robert Merkel is riding his bike through the Pyrenees to raise money from Crohn’s Disease. He wrote a few econbloggers an email asking for advice as to how best to raise funds from this exercise. He proposed some pledge based on whether he can achieve some goal in his upcoming ride.
Personally, I think they way to go is for Robert to undertake a task that creates a risk of money or embarrassment or both if he fails to achieve some goal. In effect, he needs to make a bet with his readers as to whether he will make it or not. Here is a possibility. Riding a bike is a public display. That means that if you do it wearing some goofy costume and then put the results on Flickr or YouTube that will garner some interest. Perhaps the pledges could be tied to the minutes of footage with stunned or amused French people, he is able to get.