IMF

I think this is one of the good ways to help countries in need.
As a member a country pays an amount of money, called a quota.
They look at the GDP, dept etc from a country and the quota is based on those figures.
With this money, other countries are being helped.

'cause I'm not good at explaining it in English, more info can be found on their site:
http://www.imf.org/external/index.htm

Ok, this system could be optimized, but it's already a good start.
Of course there are better ways, but his contributes too.