Just having money to donate is only half of the work. Knowing where this money can be put to good use is the other half.
Those among us who are in the position to have surplus wealth are blessed with the opportunity to think about helping the common good. Whether you do this on a personal or on a company level you probably have your own reasons. Even those most self-centered or hedonistic among us probably realize that by helping the world become a better place they also help themselves enjoy it more.
Here is what I would consider to be good ways to spend some of your surplus wealth.
Give to an established foundation [easy, immediate expenditure, low control]
This is a quick and easy way to spend your money, without too much effort.
Globally you can find organizations like the Open Philanthropy Project (see here for some of the causes they are investigating) or Network for Good (global library of established foundations) that will take good care of your money and pass it in a transparent way to causes that are for the common good of the world.
With a little effort you can probably also find a local foundation with a cause that aligns with your own aspirations in life. This kind of effort will be a bit harder but will allow for a bit more control with the way the money will be spent.
Help a startup [some effort, some control]
Startups are a hot trend around the world. They are empowering people by allowing them to take their destiny into their own hands. They are also a massive asset for any economy, capable of changing the entire eco-system of countries (like for example in Israel). This is especially true for poor economies, where startups are probably the best long-term solution. And with the improvement of economy everything will change for the better.
If you want to help a startup the best way is to find a local one that you like, through online startup communities.
Help education [some effort, long-term results]
Personally I think this approach yields the best results alas over longest period of time. Better education will create good citizens (probably like you) and will help speed up innovation which will in turn create more startups and better economy.
Depending on how much money you have, you can start locally. Find the best teachers you know or those that you were particularly fond of during your own education and donate funds to them and the projects they are working on. Teachers are often forgotten in every society and this kind of recognition for their work will mean a lot to them. And if they were good for you, they are also good for thousands of kids they will be teaching during their career which makes this effort scalable.
This approach requires some long-term thinking, but there is no better way to ensure a better world than by improving education.