Use your computer idle time for a great cause
Slightly off-topic, but still relevant when it comes to helping others. When you are doing nothing with your computer you can let a screensaver run, or you can use your computer power to help global projects. These project make use of your computer power (only when you are not using your computer power yourself) for some goal.
You can simply download a screensaver that does the work, like this BBC climate change program.
Or you can get a program where you have more control over what project you support. To get the program to run, this is the download link.
Here you find a list of the projects you can sign your computer on for. So I picked http://boinc.bakerlab.org/rosetta (in the BOINC program, when they ask for an URL of the project), a project that might help cure diseases.