Contribute to Open Source and put that on your resume (eg: a description of your contributions). I regularly mentor several students each year with OpenWISP in programs like Google Summer of Code and others, students that worked with us have been hired for internships at Microsoft and Fidelity.
Choose one in a field or industry you like, try to use it, contribute as you can, get in touch with the rest of the community, ask them what you can do to help.