There are two sites that use online ads to provide funds for charity. You just load the site, click the button and they donate to a charity.
The first is FreeKibble.com which has a page to donate dog kibble, one to donate cat kibble and one to donate cat litter. The two kibble sites feature a trivia question of the day which is fun and right or wrong your click counts.
The second is GreaterGood.com which has several charities including animals, breast cancer and literacy. There are no questions, just load the page and click the button.
For these sites, I let the pages completely load to let all of the ads load to maximize their revenue.
Each site lets you contribute once a day.