I would like to invest some money for charity. What do you think which one needs the most, and what are your arguments for that?
Every charity will say they need it the most. I'd say, go to a local charity organization. If you'd need information about investing in other things though, I found an interesting mail about it here: http://goop.com/newsletter/50/en/
I agree with Aquarezz - go local and put the money back into your community. Find something you would like to support in your community - a scholarship program, animal shelter, food bank, etc. and find out how they manage their money. I always want to see the administrative budget so check out how much of my donation will go to help the cause versus go for overhead or administrative costs, such as salaries. If you do want to or have enough money to donate beyond your community, there's always kiva [dot] org.
It is nice to hear that you would do something for charity. However, first think in your own mind- what kind of charity work you would like to finance- there are so many different ways of it. Further find out which one are genuine one for the cause and really in need of funds. Further ascertain can you countercheck the use of your funds when once given to them. Can you personally visit or keep a track of things by some way and thereafter take a decision.