i've found a couple sites that will donate money to charities just by either people clicking on the site or by playing a game.
the first is ripple. you can go to the page and click on an item and by viewing the ad appears on the page (for me its always a coopers beer ad, i think this may change depending on where in the world your server is) the sponsor donates money to the charity listed. it also has a facebook application you can apply and cool links to add to blogs (note the link under my about me section-- you can click there and a donation will be made). ripple also has a search engine (powered by google) and for every search done, the sponsor will donate a small amount (but it only works from the ripple homepage where you see the sponsor name below the box where you type in your search words, if you do it again from the results page, no donation is made (even though the ripple logo is there, the sponsor name isn't-- its all in the faq's on ripple). you can even add a ripple search bar or a little ripple button to a google search bar to make it easy to do ripple searches. a quick easy way to help food, water, education and money to those who need it.
another way (that's a bit of a time waster but if you're gonna waste time it might as well be for a good cause-- and it might even make you a little smarter) to help feed people is free rice. basically its a vocabulary game. you click on the right definition for a word and for every right answer 20 grains of rice are donated (well a sponsor of the site will donate the equivalent amount for that many grains thru the united nations world food program). the game automatically adjusts the vocab level based on your right and wrong answers so any vocab level can play and the more you play the more words you may learn and the higher vocab level you'll get to.