Crowdrise aims to make raising money for a cause not just easy, but also fun. Setting up a page to support something you care about takes less than a minute. Then, friends and family can be invited to be sponsors by donating any amount of money, large or small. You don’t have to run a marathon. You can volunteer at a soup kitchen or do whatever strikes your fancy. But Ms. Wittenberg, who has already sent her e-mail to 33,000 runners based in the United States and will soon send one to the 27,000 or so based elsewhere, hopes that anyone running in New York on Nov. 7 will use Crowdrise to do it for charity.