Social/Professional networking is definately your strongest ally. However, it is less who you know and more "Who knows you and knows what you know."
The idea is to let people know what you do, what you want to do, your ambitions, your work ethic and desire to make a qualitative difference at any company you serve.
When you have done that effectively, your sphere of exposure is greatly expanded. For instance, someone who knows the above about you, may be in a meeting a week from now. You are not there. The person they meet with expresses the desire to find someone who can do "x". "x" being one of those things you do or want to do. Your name is entered in the conversation.
Suddenly, you are not an outsider - one of many responded to a want-ad (the least attractive and the most risky place for employers to find talent). You become the only candidate and one who is referred in. You are held in higher regard.
It is simple. We like doing work with people we know or with people referred to us because anyone new is a higher risk/unknown commodity.
That being said, job boards are one part - perhaps the most passive, least effective part, of a job search. Instead, visit some local companies - whether they have posted jobs or not. Don't just visit the larger companies. I company with 35-200 employees may be just the place to get valuable experience and exposure.
Good Luck!
Matthew Moran (career blog and podcast below)
Career Advice with Attitude for the IT Pro