Distinguish yourself from many other computer science students with knowledge and experience that is in demand.
Demonstrate the way you work
Work collaboratively on teams with people all over the world to solve actual problems.
Increase your visibility
Build a codebase that you can show to potential employers—while working with people who could become those employers.
Increase your value
Be more in demand and potentially command a higher salary.
Work on humanitarian projects that help solve problems—like directing disaster relief efforts or allowing mobility-limited individuals to control a computer via eye movements—and develop skills valuable in many situations.