aka Volunteering Overseas
I spent a week volunteering in Swaziland at an orphanage a few years ago, we did things like install rain gutters on houses that were being fixed up for the kids, hung out with the kids, and I even plowed a field!
My recommendation would be to make sure the company you are thinking about volunteering with is a reputable one. Some companies have turned voluntourism into a for-profit situation and will charge you thousands of dollars for you to volunteer and very little of the money actually makes it to the organization that you are looking to help out.
However, there are some companies that will charge a higher rate (than if you were to do it yourself) but they make it very simple for you, generally looking after your accommodations, meals, travel insurance, and sometimes even offer extra options like language classes. If you are new to traveling this could be a good way to break into volunteering overseas.
If you are an experienced traveler I would suggest doing all of that yourself, it will save you money and you can pour more of yourself into the organization that you are looking to support.
This is the best resource for overseas volunteering that I have come across so far if you are looking to do it yourself, however it is only specific to South America: Volunteer South America.
Check back for updates as I will be providing more information here as soon as I have some time to do some more reasearch!