This is a semi-regular pitch for the Greater Good suite of pages, which donate to various charities every time someone clicks. While any page in the suite can be a jumpoff, I usually start at the Hunger Site, which donates food to famine areas or those hit by natural disasters.
I recommend bookmarking http://www.thehungersite.com and making a daily routine of visiting/clicking (only one click per day counts). There are also tabs to the other click-to-give sites which help underwrite mammograms for needy women; feed animals in shelters; help homeless veterans; help pay for therapy for people with autism; contribute to health care for children; buy books for poor children; and buy up land in the rainforest in order to preserve it. Just to clarify -- you can click each tab once per day; you don't need to choose between them.
The hungersite as well as two of its companion sites are vetted as true by Snopes: http://www.snopes.com/inboxer/charity/hungersite.asp.
Finally, as the holiday season approaches, please consider shopping at small local businesses rather than large chains. However, if you just can't find that one special gift, please look at the Greater Good stores. Each of the tabs has a link to the store, and by following the link from any individual tab, all proceeds are given to the charity which was selected. For instance, to benefit breast cancer research, I would enter the store from the breast cancer tab. There are a ton of products of all kinds, and they are fairly traded, many from small collectives which benefit the poorest of the poor. Not only can you find some really cool stuff, but all proceeds/profits are donated.