Get a summer internship - GSOC is wonderful, but plenty of software engineering firms hire summer interns with whom they may develop a relationship that turns into a full-time position after graduation. You're a bit late to be looking for this summer, but some places may still have openings. Your career office may be able to help you, but in my experience the best way to network is to think of people you already know in industry.
Do a Co-Op Program - co-ops are like long internships that usually last a summer plus a semester. They get you a chance to really delve into real problems at a company and you usually get college credit for them. If you have space in your academic schedule, consider it.
Contribute to an open source project - some people are of the firm mindset that a github commit log is the best CV you can have. Find an open source project where you can help out. You may want to just start with adding documentation on features that you initially found confusing or offering to do some code clean-up. If you feel more confident try tackling new features or bug fixes. As a bonus you can do this throughout the year.